Change docs links to actual file extension (.md)

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

Change-Id: Ia4a2f8a1bcc434380b8b0f84a5fb43f9d256281a
3 files changed
tree: 06680e6d5c56ba429a7bb56673ba16cc44fdc297
  1. BUCK
  2. LICENSE
  3. src/