Merge "[Thread] add public newbie guide" into main am: 53f4a29816 am: 43b971e2e9

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3007440

Change-Id: I78a97782f0b7c08f1ddbf3c51e204854688bd761
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>