CLDR-18463 Update InfoHub: fix link, add Concentrations section (#4616)

Author: pedberg-icu

docs/site/translation.md

@@ -57,10 +57,11 @@ As new locales reach Basic Coverage, their language names have been added for lo
 
 #### Core/Extensions
 
-There is a new mechanism for better menu names. When you see a **Code** with `-core` or `-extension`, please read [Core and Extensions](/displaynames/languagelocale-names#core-and-extensions).
+There is a new mechanism for better menu names. When you see a **Code** with `-core` or `-extension`, please read [Locale Option Value Names](/translation/displaynames/locale-option-names-key#locale-option-value-names).
 
 #### Scripts
 
+
 There are 5 new scripts for Unicode 17. Currently the names are in English: Beria Erfe, Chisoi, Sidetic, Tai Yo, Tolong Siki.
 Coverage for other languages is at comprehensive. 
 <!-- I don't think we want to encourage this: ... if there is a need to have coverage at lower level in some locale,
@@ -164,6 +165,8 @@ The keys for two units changed (the translations can probably remain the same) a
 **Please check over the values for `concentr-part-per-1e6` and `concentr-part-per-1e9` in your locale.
 Some languages had used the equivalent of "millionths" instead of the equivalent of "parts per million".**
 
+For more information see [Concentrations](/translation/units/unit-names-and-patterns#concentrations).
+
 #### Many new units in English
 
 Mnny new units were added in English. 

docs/site/translation/units/unit-names-and-patterns.md

@@ -128,4 +128,10 @@ If the natural word for both "point" and "dot" is the same, such as *punkt*, the
 
 A few languages have special words for **year, month, week,** or **day** when they are used in context of a person's age. Other languages may simply use the same terms for each one, and do not require separate translation.
 
+### Concentrations
+
+There are certain predefined units for concentrations, such as `part-per-1e6` “parts per million” and `part-per-1e9` “parts per billion”.
+In addition there is a component `part` “parts” (new in CLDR 48) that can be used in conjunction with the `per` pattern to compose
+arbitrary concentrations such as “parts per 100,000”.
+