docs: Remove outdated comment

Author: ZedThree

manual/sphinx/conf.py

@@ -95,7 +95,6 @@ def __getattr__(cls, name):
     sys.path.append("bout_build/tools/pylib")
 
 
-# readthedocs currently runs out of memory if we actually dare to try to do this
 if has_breathe:
     # Run doxygen to generate the XML sources
     if on_readthedocs: