Merge "More documentation for C++ global config." into main am: eae6635a am:...

Merge "More documentation for C++ global config." into main am: eae6635a am: 2cf42655 am: b9d2d04d am: b0bf4aac

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2770218



Change-Id: Ie119006a6d17bc865b165eb2e152085fbb82a9d4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>