Revise "reStructuredText Directives" plus small documentation updates.
Update HISTORY.
Small additions for "The Docutils Document Tree".
Fix option name and link in "Docutils Configuration".
Adapt link in "reStructuredText Interpreted Text Roles".
"reStructuredText Directives":
* Sort option lists by name.
* Use ``literal`` for directive option names
(except when the name is also a hyperlink).
* Provide more cross-links.
* Repeat option name in introduction sentence to the option list.
* Use space (instead of hyphen) in ``_class option:`` hyperlink target
(no change to the generated id).
* Shorten descriptions if possible without loss of clarity.
git-svn-id: http://svn.code.sf.net/p/docutils/code/trunk@9551 929543f6-e4f2-0310-98a6-ba3bd3dd1d04