Change docs links to actual file extension (.md)

See https://gerrit-review.googlesource.com/83950 for detailed context.

Change-Id: I674c1f6eab6ed28956fbb685c83c88f87ac015f5
1 file changed
tree: 5a9225b06f92fdf6005758dc2645f195114ca19a
  1. lib/
  2. src/
  3. .buckconfig
  4. .gitignore
  5. BUCK