Clarify some comments

Based on the info in this Qt blog post:
https://www.qt.io/blog/qt-on-apple-silicon

.github/workflows/build.yaml

@@ -160,8 +160,8 @@ jobs:
         - { cc: gcc-14, cxx: g++-14, coverage: false }
         - { cc: gcc-14, cxx: g++-14, coverage: true }
         exclude:
-          # GitHub's macOS 14+ gcc can only target arm64, but the Qt Online Installer only provides ARM64 for Qt 6.2+,
-          # so exclude Qt 5.x (and 6.1, 6.2) with GCC on macOS 14+. Also see the `arch` step below for more details.
+          # GitHub's macOS 14+ gcc can only target arm64, but Qt didn't add Apple arm64 support until Qt 6.2, so:
+          # Exclude Qt 5.x (and 6.0, 6.1) with GCC on macOS 14+. Also see the `arch` step below for more details.
           - { qt: '5.9.9',   os: macos-14, env: { cc: gcc-14 } }
           - { qt: '5.9.9',   os: macos-15, env: { cc: gcc-14 } }
           - { qt: '5.10.1',  os: macos-14, env: { cc: gcc-14 } }
@@ -212,7 +212,7 @@ jobs:
     - name: Choose target architectures
       id: arch
       run: |
-        # Qt Online Installer only provides x86-64 binaries (not arm64) prior to Qt 6.2.0.
+        # Qt only supports x86-64 (not arm64) on macOS prior to Qt 6.2.0. See https://www.qt.io/blog/qt-on-apple-silicon
         if [[ '${{ matrix.qt }}' =~ ^(5|6\.[01])\. ]]; then arch=x86_64
         # GitHub runners' (homebrew'd) gcc's only support support x86-64 prior to macos-14, and only arm64 after.
         # Note: if we attempt to use multiple archs, gcc will warn, but continue, resulting in later failures.