Add link to the Android Build Explorer with target to select a build.

Target: aosp_arm64-trunk_staging-userdebug

This could help the user directly pick the right build.

Bug: 409768276 
Test: atest --host AndroidGlobalLintCheckerTest
Flag: EXEMPT README
Change-Id: Idf877e676f00f28e94b1dee2f50adbc200e507ae