Fix epydoc error in rlib2.py

I blindly assumed epydoc would use normal reST, but turns out it uses
its own “epytext” in our configuration. Since the latter doesn't support
blockquotes, I just make the paragraph a literal block.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>