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

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



Change-Id: If292d4d82e9ba799b1eb91dbaedb53634ec77908
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>