Migrate Rules docs from Native rules to Starlark Rules

[ahumesky]

The docs for the Android rules (https://bazel.build/reference/be/android) are derived from the Native rules. The docs should be migrated to derive from the Starlark rules. (In particular, once the native rules are deleted, the docs at https://bazel.build/reference/be/android will disappear). The docs also should be updated to use the Starlark rules

[ahumesky]

This is complete: https://bazelbuild.github.io/rules_android/