Fix docs to support beta detection

Author: BobDotCom

docs/conf.py

@@ -102,7 +102,7 @@
 release = version
 
 # This assumes a tag is available for final releases
-branch = "master" if version.endswith("a") else "v" + version
+branch = "master" if version.endswith("a") or version.endswith("b") else "v" + version
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.