Recommend bootstrapping a stable version of Buck

The tip of the Buck tree may not compile. It happens, software is
fuzzy and humans make mistakes.

The version of Buck used by .buckversion in Gerrit is more likely to
be known to build.  Recommend checking out that version to start a new
workspace for Gerrit.

Change-Id: Idad3a461e40a0b0e2103231827b3935d37d52566
1 file changed