doc: make paragraphs before example code end with "::" for reST syntax This prevents lines in an example code from being treated as a part of normal paragraph. For issue example, lines are folded into one paragraph.

syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes