ICU-23056 some ICU 78 download page updates

See #3711

Author: markusicu

docs/download/78.md

@@ -32,45 +32,26 @@ including new characters and scripts, emoji, collation & IDNA changes, and corre
 
 It also updates to
 [CLDR 48](https://cldr.unicode.org/downloads/cldr-48)
-([alpha blog](https://blog.unicode.org/2025/09/unicode-cldr-48-alpha-available-for.html))
+([beta blog](https://blog.unicode.org/2025/10/unicode-cldr-48-beta-available-for.html))
 locale data with new locales, and various additions and corrections.
 
-TODO: High-level summary
+In Java, there is a draft new Segmenter API which is easier and safer to use than BreakIterator.
+In C++, there is a new set of APIs for Unicode string (UTF-8/16/32) code point iteration
+that works seamlessly with modern C++ iterators and ranges.
 
-ICU 78 and CLDR 48 are major releases, including a new version of Unicode and major locale data improvements.
+The Java implementation of the
+[CLDR MessageFormat 2.0 specification](https://www.unicode.org/reports/tr35/tr35-messageFormat.html)
+has been updated to CLDR 48.
+The core API has been upgraded to “draft”, while the Data Model API remains in technology preview.
 
-TODO status update:
-The Java technology preview implementation of the CLDR MessageFormat 2.0 specification has been updated to incorporate the
-[CLDR 46.1 spec](https://www.unicode.org/reports/tr35/tr35-74/tr35-messageFormat.html)
-plus most but not all of the CLDR 47 changes.
+The C++ implementation of MessageFormat 2.0 is at CLDR 47 level and remains in technology preview.
 
-TODO status update:
-The C++ technology preview implementation of MessageFormat 2.0 is not yet quite up to date with CLDR 46.1.
+ICU 78 and CLDR 48 are major releases, including a new version of Unicode and major locale data improvements.
 
 For more details, including migration issues, see below.
 
-Please use the [icu-support mailing list](https://icu.unicode.org/contacts) and/or [find/submit error reports](https://icu.unicode.org/bugs).
-
-### Attention: Future Changes
-
-TODO status update:
-Beginning with ICU 78 (2025-oct):
-
-1. We want to move the minimum required Java version from Java 8 to Java 11.
-   This is a significant, useful update in terms of the Java language and
-   standard library, and simplifies ICU tooling which currently uses
-   a mix of Java 8 and Java 11.
-   Note that [Android desugaring](https://developer.android.com/studio/write/java11-default-support-table)
-   supports at least Java 11 since late 2023.\
-   See [ICU-23072](https://unicode-org.atlassian.net/browse/ICU-23072)
-   where you can provide comments.
-2. We are planning to remove the
-   [ICU4J Locale Service Provider](../userguide/icu4j/locale-service-provider.md)
-   ([Maven: com.ibm.icu / icu4j-localespi / version 77.1](https://mvnrepository.com/artifact/com.ibm.icu/icu4j-localespi/77.1)).
-   It is much less useful than when we added it, has very low usage,
-   needs work for newer Java versions, and complicates ICU4J development.\
-   See [ICU-23071](https://unicode-org.atlassian.net/browse/ICU-23071)
-   where you can provide comments.
+Please use the [icu-support mailing list](https://icu.unicode.org/contacts) and/or
+[find/submit error reports](https://icu.unicode.org/bugs).
 
 ### Version Number
 
@@ -85,8 +66,23 @@ Note: There may be additional commits on the [maint/maint-78](https://github.com
 
 ## Common Changes
 
+* [Unicode 17](https://www.unicode.org/versions/Unicode17.0.0/)
+  ([blog](https://blog.unicode.org/2025/09/unicode-170-release-announcement.html)):
+  * Adds two modern-use scripts: Beria Erfe & Tolong Siki
+  * Adds two historic scripts & more than 4300 new CJK ideographs
+  * New currency sign: SAUDI RIYAL SIGN
+  * Eight new emoji characters
+  * Segmentation improvements (word & line breaking)
+  * Identifiers & security:
+    The majority of CJK ideographs, the Bopomofo script,
+    and more than 1100 other pre-Unicode 17 characters,
+    are no longer recommended for use in identifiers by default
+    (Identifier_Status & Identifier_Type properties),
+    after thorough review.
+    * For CJK ideographs, only 19,842 that are in modern common use (out of now more than 100,000)
+      remain recommended for default identifier use.
 * [CLDR 48](https://cldr.unicode.org/downloads/cldr-48)
-  ([alpha blog](https://blog.unicode.org/2025/09/unicode-cldr-48-alpha-available-for.html)):
+  ([beta blog](https://blog.unicode.org/2025/10/unicode-cldr-48-beta-available-for.html)):
   * TODO: old news here
   * No major data collection for existing locales; focus on bug fixes and structural improvements
   * New regional variants: English in several European countries, and Cantonese in Macau (`yue_Hant_MO`)
@@ -107,6 +103,8 @@ Note: There may be additional commits on the [maint/maint-78](https://github.com
 ## ICU4C Specific Changes
 
 * [API changes since ICU4C 77 (Markdown)](https://github.com/unicode-org/icu/blob/maint/maint-78/icu4c/APIChangeReport.md) / [(HTML)](https://htmlpreview.github.io/?https://github.com/unicode-org/icu/blob/maint/maint-78/icu4c/APIChangeReport.html)
+  * TODO: In C++, there is a new set of APIs for Unicode string (UTF-8/16/32) code point iteration
+    that works seamlessly with modern C++ iterators and ranges.
   * TODO: old news here
   * New APIs for colloquial C++ use of C USet ([ICU-22876](https://unicode-org.atlassian.net/browse/ICU-22876))
     and C UCollator ([ICU-22879](https://unicode-org.atlassian.net/browse/ICU-22879))
@@ -120,18 +118,28 @@ Note: There may be additional commits on the [maint/maint-78](https://github.com
 
 ## ICU4J Specific Changes
 
+* The minimum required Java version has been upgraded from Java 8 to Java 11.
+  ([ICU-23072](https://unicode-org.atlassian.net/browse/ICU-23072))\
+  This is a significant, useful update in terms of the Java language and
+  standard library, and simplifies ICU tooling.
+  Note that [Android desugaring](https://developer.android.com/studio/write/java11-default-support-table)
+  supports at least Java 11 since late 2023.
 * [API Changes since ICU4J 77](https://htmlpreview.github.io/?https://github.com/unicode-org/icu/blob/maint/maint-78/icu4j/APIChangeReport.html)
-* TODO: old news here
-* The Java technology preview implementation of the CLDR MessageFormat 2.0 specification has been updated to incorporate the
-  [CLDR 46.1 spec](https://www.unicode.org/reports/tr35/tr35-74/tr35-messageFormat.html)
-  plus most but not all of the CLDR 47 changes.
+  * TODO: In Java, there is a draft new Segmenter API which is easier and safer to use than BreakIterator.
+* We have removed the
+   [ICU4J Locale Service Provider](../userguide/icu4j/locale-service-provider.md)
+   ([ICU-23071](https://unicode-org.atlassian.net/browse/ICU-23071))\
+   ([Maven: com.ibm.icu / icu4j-localespi / version 77.1](https://mvnrepository.com/artifact/com.ibm.icu/icu4j-localespi/77.1)).
+   It had become much less useful than when we added it and had very low usage.
+   Projects that used it should call ICU4J directly instead.
+* The Java implementation of the
+  [CLDR MessageFormat 2.0 specification](https://www.unicode.org/reports/tr35/tr35-messageFormat.html)
+  has been updated to CLDR 48.
+  The core API has been upgraded to “draft”, while the Data Model API remains in technology preview.
 
 ## Known Issues
 
-* TODO: old news here
-* The new MeasureUnit for `portion-per-1e9` works for formatting,
-  but when the new member function `getConstantDenominator()` is called on this unit,
-  it incorrectly returns 0. ([ICU-23045](https://unicode-org.atlassian.net/browse/ICU-23045))
+* (none yet)
 
 ## Migration Issues
 
@@ -148,26 +156,28 @@ We routinely test on recent versions of Linux, macOS, and Windows.
 
 We accept patches for other platforms.
 
-Windows: The minimum supported version is Windows 7. (See [How To Build And Install On Windows](../userguide/icu4c/build.html#how-to-build-and-install-on-windows) for more details.)
+Windows: The minimum supported version is Windows 7.
+(See [How To Build And Install On Windows](../userguide/icu4c/build.html#how-to-build-and-install-on-windows)
+for more details.)
 
 ## ICU4J Platform Support
 
-ICU4J works on Java 11..21 (at least).
+ICU4J works on Java 11..25 (at least).
 
 ICU4J should work on Android API level 21 and later but may require “[library desugaring](https://developer.android.com/studio/write/java8-support#library-desugaring)”.
 
 ## Download
 
 ### GitHub
 TODO rc tag:
-Source and binary downloads are available on the git/GitHub tag page: <https://github.com/unicode-org/icu/releases/tag/release-78-1>
+Source and binary downloads are available on the git/GitHub tag page: <https://github.com/unicode-org/icu/releases/tag/release-78.1rc>
 
 See the [Source Code Setup](../devsetup/source/) page for how to download the ICU file tree directly from GitHub.
 
 ICU locale data was generated from CLDR data equivalent to:
 
-* <https://github.com/unicode-org/cldr/releases/tag/release-48-beta1>
-* <https://github.com/unicode-org/cldr-staging/releases/tag/release-48-beta1>
+* <https://github.com/unicode-org/cldr/releases/tag/release-48-beta2>
+* <https://github.com/unicode-org/cldr-staging/releases/tag/release-48-beta2>
 
 ### Maven
 * TODO: not published yet