Update docgen.py
Update docgen.py

Fix a RexAnalyzer error during the import, and update in github as well. 

Parentheses around a single item in Python has no effect: (foo) is exactly equivalent to foo. In many cases this is harmless, but it can suggest a subtle bug when used in string formatting.  A '%'-formatted string with a single format specifier can be formatted using a single value or a one element tuple: 'hello %s' % name or 'hello %s' % (name,). Consequently, a line like error_msg = 'Cannot process %s' % (data) may leave code reviewers and future readers unsure if there is a subtle bug if data is a tuple. 

Since the args.repo_owner here is a single string, drop the parentheses is better.
firebase/grpc,ejona86/grpc,firebase/grpc,jtattermusch/grpc,ejona86/grpc,donnadionne/grpc,stanley-cheung/grpc,vjpai/grpc,nicolasnoble/grpc,grpc/grpc,donnadionne/grpc,nicolasnoble/grpc,donnadionne/grpc,stanley-cheung/grpc,nicolasnoble/grpc,firebase/grpc,nicolasnoble/grpc,ejona86/grpc,vjpai/grpc,vjpai/grpc,ctiller/grpc,jtattermusch/grpc,jtattermusch/grpc,grpc/grpc,jtattermusch/grpc,ctiller/grpc,grpc/grpc,jtattermusch/grpc,vjpai/grpc,firebase/grpc,nicolasnoble/grpc,stanley-cheung/grpc,donnadionne/grpc,nicolasnoble/grpc,nicolasnoble/grpc,vjpai/grpc,donnadionne/grpc,donnadionne/grpc,nicolasnoble/grpc,ejona86/grpc,grpc/grpc,stanley-cheung/grpc,grpc/grpc,grpc/grpc,donnadionne/grpc,ejona86/grpc,firebase/grpc,firebase/grpc,ctiller/grpc,stanley-cheung/grpc,stanley-cheung/grpc,ctiller/grpc,firebase/grpc,jtattermusch/grpc,ejona86/grpc,stanley-cheung/grpc,vjpai/grpc,grpc/grpc,ctiller/grpc,firebase/grpc,donnadionne/grpc,ctiller/grpc,stanley-cheung/grpc,ejona86/grpc,ctiller/grpc,nicolasnoble/grpc,ejona86/grpc,grpc/grpc,stanley-cheung/grpc,ctiller/grpc,stanley-cheung/grpc,grpc/grpc,donnadionne/grpc,stanley-cheung/grpc,firebase/grpc,jtattermusch/grpc,donnadionne/grpc,firebase/grpc,vjpai/grpc,ctiller/grpc,ejona86/grpc,vjpai/grpc,jtattermusch/grpc,ctiller/grpc,ejona86/grpc,firebase/grpc,donnadionne/grpc,jtattermusch/grpc,vjpai/grpc,vjpai/grpc,ctiller/grpc,ejona86/grpc,vjpai/grpc,donnadionne/grpc,jtattermusch/grpc,grpc/grpc,nicolasnoble/grpc,firebase/grpc,grpc/grpc,nicolasnoble/grpc,jtattermusch/grpc,ejona86/grpc,jtattermusch/grpc,stanley-cheung/grpc,grpc/grpc,ctiller/grpc,vjpai/grpc,nicolasnoble/grpc