Add releases to Mynewt repository.yml

This makes it possible to setup Mynewt project which checkouts
specified version of tinyusb.

repository.yml

@@ -1,5 +1,12 @@
 repo.name: tinyusb
 repo.versions:
     "0.0.0": "master"
+    "0.5.0": "0.5.0"
+    "0.6.0": "0.6.0"
+    "0.7.0": "0.7.0"
+    "0.8.0": "0.8.0"
+    "0.9.0": "0.9.0"
+
+    "0-dev": "0.0.0"        # master
+    "0-latest": "0.9.0"     # latest stable release
 
-    "0-dev": "0.0.0"