Add a direntry to the Rottlog info manual.

diff --git a/doc/rottlog.texi b/doc/rottlog.texi
index 0ba8019..0f29916 100644
--- a/doc/rottlog.texi
+++ b/doc/rottlog.texi
@@ -18,6 +18,11 @@ Documentation License.''
 @end quotation
 @end copying
 
+@dircategory System administration
+@direntry
+* Rottlog: (rottlog).         The GNU log management utility.
+@end direntry
+
 @paragraphindent none
 
 @iftex
ef='/'><img src='https://git.koszko.org/cgit-static/cgit.png' alt='cgit logo'/></a></td>
<td class='main'><a href='/'>index</a> : <a href='/guix/'>guix</a></td><td class='form'><form method='get'>
<input type='hidden' name='id' value='ed0b773ff6fafdb6ec89b29f16c07478904ca943'/><select name='h' onchange='this.form.submit();'>
<option value='koszko' selected='selected'>koszko</option>
<option value='koszko-scripts'>koszko-scripts</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>refs</a><a class='active' href='/guix/log/tests/upstream.scm'>log</a><a href='/guix/tree/tests/upstream.scm?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>tree</a><a href='/guix/commit/tests/upstream.scm?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>commit</a><a href='/guix/diff/tests/upstream.scm?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/upstream.scm'>
<input type='hidden' name='id' value='ed0b773ff6fafdb6ec89b29f16c07478904ca943'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>root</a>/<a href='/guix/log/tests?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>tests</a>/<a href='/guix/log/tests/upstream.scm?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943'>upstream.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/upstream.scm?id=ed0b773ff6fafdb6ec89b29f16c07478904ca943&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-01-28 23:13:40 +0100'>2019-01-28</span></td><td><a href='/guix/commit/tests/upstream.scm?id=ea6fb108f6a3a53d48ea187b1f82b5f7ffce00a7'>upstream: Temporarily skip failing test.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/upstream.scm ("coalesce-sources same version"): Skip.
</span></span></td><td>Ludovic Courtès</td></tr>