templatekw/help: document the {parents} keyword
The {parents} keyword does not appear in the generated documentation for
templates because it is added by `changeset_templater` (and this is because
its behavior depends on `ui`, so it can't be defined as a normal template
keyword; see comments in `changeset_templater._show()`).
Add it to the documentation synthetically by creating a stub documentation
function.
Test plan: built the docs and examined the man page to verify that this
keyword is now documented. I'm not sure how to test the i18n extraction part,
but assume it will just work given that this patch doesn't do anything too
crazy.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<!-- This is the second screen displayed during the install. -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta http-equiv="Content-Style-Type" content="text/css">
<title></title>
<style type="text/css">
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Helvetica}
p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px}
p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica}
p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; color: #000fed}
span.s1 {text-decoration: underline}
span.s2 {font: 12.0px Courier}
</style>
</head>
<body>
<p class="p1"><b>Before you install</b></p>
<p class="p2"><br></p>
<p class="p3">This is an OS X 10.6 version of Mercurial that depends on the default Python 2.6 installation.</p>
<p class="p2"><br></p>
<p class="p1"><b>After you install</b></p>
<p class="p2"><br></p>
<p class="p3">This package installs the <span class="s2">hg</span> executable in <span class="s2">/usr/local/bin</span> and the Mercurial files in <span class="s2">/Library/Python/2.6/site-packages/mercurial.</span></p>
<p class="p2"><br></p>
<p class="p1"><b>Documentation</b></p>
<p class="p2"><br></p>
<p class="p3">Visit the <a href="http://mercurial.selenic.com/">Mercurial web site and wiki</a></p>
<p class="p2"><br></p>
<p class="p3">There's also a free book, <a href="http://hgbook.red-bean.com/">Distributed revision control with Mercurial</a></p>
<p class="p2"><br></p>
<p class="p1"><b>Reporting problems</b></p>
<p class="p2"><br></p>
<p class="p3">If you run into any problems, please file a bug online:</p>
<p class="p3"><a href="http://mercurial.selenic.com/bts/">http://mercurial.selenic.com/bts/</a></p>
</body>
</html>