This ticket fixes some errors in Sage 9.4 reference manual arising from recently merged code. This regards

• missing :: before a doctest block
• incorrect hyperlinks
• docstring started by """ instead of r""", so that \theta is interpreted by Sphinx as a tabulation + heta.
• an ill-placed .. NOTE:: (cut-and-paste typo)

CC: @mkoeppe @mjungmath

Component: documentation

Author: Eric Gourgoulhon

Branch/Commit: 4bc9aa9

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32457