Update version numbers

Author: AustinBenoit

cpp_sdk_version.json

@@ -1,5 +1,5 @@
 {
-  "released": "13.5.0",
-  "stable": "13.5.0",
-  "head": "13.5.0"
+  "released": "13.6.0",
+  "stable": "13.6.0",
+  "head": "13.6.0"
 }

release_build_files/readme.md

@@ -613,8 +613,8 @@ workflow use only during the development of your app, not for publicly shipping
 code.
 
 ## Release Notes
-### Upcoming
-- Changes 
+### 13.6.0
+- Changes
     - Functions (general): Add in support for Limited Use Tokens.
     - Storage: Added `List` API for all platforms, which gets the list of items under a `StorageReference`