Add README.md

README.md

+# Bramble specification
+
+- [Binary Data Format](BDF.md)
+- [Bramble Handshake Protocol](protocols/BHP.md)
+- [Bramble QR Code Protocol](protocols/BQP.md)
+- [Bramble Rendezvous Protocol](protocols/BRP.md)
+- [Bramble Synchronisation Protocol](protocols/BSP.md)
+- [Bramble Transport Protocol](protocols/BTP.md)