Summary:
See D5561. Ref T2378.
- Add `support/bin/*` to .gitignore so any symlinks or binaries won't get picked up by Git.
- Add a README so Git preserves the directory and there's at least //some// documentation of its existence.
Test Plan: ummmmm
Reviewers: jevripio, codeblock, btrahan
Reviewed By: jevripio
CC: aran
Maniphest Tasks: T2378
Differential Revision: https://secure.phabricator.com/D5562
