Documentation fixes (#7731)
Documentation fixes (#7731)

Fixes https://github.com/flutter/flutter/issues/4620
flutter/flutter,flutter/flutter,flutter/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,turnidge/flutter,turnidge/flutter,turnidge/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,Hixie/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,turnidge/flutter,Hixie/flutter,cbracken/flutter,cbracken/flutter,cbracken/flutter,turnidge/flutter,flutter/flutter,flutter/flutter