Add BAZEL.md file with build and test instructions on all supported platforms.

Bug: skia:12400
Change-Id: If284558ccc34af3d7016ccf1df0b8f24cf51ce91
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/444976
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
1 file changed