am ba812693: cherrypick Change-Id: I52ed6e5a97f32d2395cf171009b0b650268cac4e docs: ndk r6b rel notes

* commit 'ba8126938e8ec82502e9db9594ef7036fa4a4b13':
  cherrypick Change-Id: I52ed6e5a97f32d2395cf171009b0b650268cac4e docs: ndk r6b rel notes