add underlay files for listdirectives

As was noted, 'listdirectives' didn't include the underlay files that make
it really worthwhile.  I've just gone through all the plugin
documentation, modified it to remove installation information and renamed
the files to match the directives rather than the plugins.  This can now
serve as useful underlay.

I've only gone through plugins in the 'plugins' dir.  I did not go through
the 'contrib' dir.

1 files changed, 35 insertions, 0 deletions

diff --git a/underlays/basewiki/directive/tag.mdwn b/underlays/basewiki/directive/tag.mdwn
new file mode 100644
index 000000000..68b969f76
--- /dev/null
+++ b/underlays/basewiki/directive/tag.mdwn
@@ -0,0 +1,35 @@
+The `tag` and `taglink` directives are supplied by the [[!iki plugins/tag]] plugin.
+
+These directives allows tagging pages. List tags as follows:
+
+	\[[!tag tech life linux]]
+
+The tags work the same as if you had put a (hidden) [[ikiwiki/WikiLink]] on
+the page for each tag, so you can use a [[ikiwiki/PageSpec]] match all
+pages that are tagged with a given tag, for example. The tags will also
+show up on blog entries and at the bottom of the tagged pages, as well as
+in RSS and Atom feeds.
+
+If you want a visible [[ikiwiki/WikiLink]] along with the tag, use taglink
+instead:
+
+	\[[!taglink foo]]
+	\[[!taglink tagged_as_foo|foo]]
+
+This plugin has a configuration option. Set --tagbase=tags and links to tags
+will be located under the specified base page. If ikiwiki is configured
+this way, then the example above actually tags the page with the tags
+tags/tech, tags/life, and tags/linux. This is a useful way to avoid
+having to write the full path to tags, if you want to keep them grouped
+together out of the way.
+
+If you want to override the tagbase for a particular tag, you can use
+something like this:
+
+	\[[!tag ./foo]]
+	\[[!taglink /foo]]
+
+[[!if test="enabled(tag)" then="""
+This wiki has the tag plugin enabled, so you'll see a note below that this
+page is tagged with the "tags" tag.
+"""]]