Merge bitcoin#24241: doc: cleanup doc on need of Developer Account to obtain macOS SDK

ddcac22 doc: cleanup doc on need of Developer Account to obtain macOS SDK (jarolrod)

Pull request description:

  The explicit statement that an Apple Developer Account is required in order to obtain the SDK is buried within the `Deterministic macOS DMG Notes` section. It should be the first thing mentioned under the `SDK Extraction` section.
  The reason to do this is to set expectations of what is required before starting any steps or clicking on links.

  This fixes the issue by doing just that; moving this information to the `SDK Extraction` section. Now that the information is moved, this also deletes unnecessary SDK related notes from the `Deterministic macOS DMG Notes` section. It is not necessary to explain under what sub-directory 'most' of the important files are inside of the `Xcode.app`.

  Note that this also fixes a missed Xcode version link bump by deleting it :)

ACKs for top commit:
  fanquake:
    ACK ddcac22

Tree-SHA512: 9fe7fddd66b68a0475be8b0c78cb58932bf5b68d962ece36a86f3b743a88d8561c0ec3e8d88bcaf338da7ab9d3dfcfb9399f6e1a884d83c8f3117c186d049469

Author: fanquake

contrib/macdeploy/README.md

@@ -12,12 +12,14 @@ When complete, it will have produced `Bitcoin-Core.dmg`.
 
 ### Step 1: Obtaining `Xcode.app`
 
+A free Apple Developer Account is required to proceed.
+
 Our current macOS SDK
 (`Xcode-12.2-12B45b-extracted-SDK-with-libcxx-headers.tar.gz`) can be
 extracted from
 [Xcode_12.2.xip](https://download.developer.apple.com/Developer_Tools/Xcode_12.2/Xcode_12.2.xip).
 Alternatively, after logging in to your account go to 'Downloads', then 'More'
-and look for [`Xcode_12.2`](https://download.developer.apple.com/Developer_Tools/Xcode_12.2/Xcode_12.2.xip).
+and search for [`Xcode_12.2`](https://developer.apple.com/download/all/?q=Xcode%2012.2).
 An Apple ID and cookies enabled for the hostname are needed to download this.
 The `sha256sum` of the archive should be `28d352f8c14a43d9b8a082ac6338dc173cb153f964c6e8fb6ba389e5be528bd0`.
 
@@ -78,19 +80,9 @@ This version of `cctools` has been patched to use the current version of `clang`
 and its `libLTO.so` rather than those from `llvmgcc`, as it was originally done in `toolchain4`.
 
 To complicate things further, all builds must target an Apple SDK. These SDKs are free to
-download, but not redistributable. To obtain it, register for an Apple Developer Account,
-then download [Xcode_12.1](https://download.developer.apple.com/Developer_Tools/Xcode_12.1/Xcode_12.1.xip).
-
-This file is many gigabytes in size, but most (but not all) of what we need is
-contained only in a single directory:
-
-```bash
-Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk
-```
-
-See the SDK Extraction notes above for how to obtain it.
+download, but not redistributable. See the SDK Extraction notes above for how to obtain it.
 
-The Guix process build 2 sets of files: Linux tools, then Apple binaries which are
+The Guix process builds 2 sets of files: Linux tools, then Apple binaries which are
 created using these tools. The build process has been designed to avoid including the
 SDK's files in Guix's outputs. All interim tarballs are fully deterministic and may be freely
 redistributed.