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, 43 insertions, 0 deletions

diff --git a/underlays/basewiki/directive/postsparkline.mdwn b/underlays/basewiki/directive/postsparkline.mdwn
new file mode 100644
index 000000000..d10451f85
--- /dev/null
+++ b/underlays/basewiki/directive/postsparkline.mdwn
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+The `postsparkline` directive is supplied by the [[!iki plugins/postsparkline]] plugin.
+
+This plugin uses the [[!iki plugins/sparkline]] plugin to create a [[sparkline]] of
+statistics about a set of pages, such as posts to a blog.
+
+# examples
+
+	Post interval: 
+	\[[!postsparkline pages="blog/* and !*/Discussion" max=100
+	formula=interval style=bar barwidth=2 barspacing=1 height=13]]
+	
+	Posts per month this year: 
+	\[[!postsparkline pages="blog/* and !*/Discussion" max=12
+	formula=permonth style=bar barwidth=2 barspacing=1 height=13]]
+
+# usage
+
+All options aside fron the `pages`, `max`, `formula`, `time`, and `color`
+options are passed on to the sparkline plugin.
+
+You don't need to specify any data points (though you can if you want to).
+Instead, data points are automatically generated based on the creation
+times of pages matched by the specified `pages` [[ikiwiki/PageSpec]]. A
+maximum of `max` data points will be generated.
+
+The `formula` parameter controls the formula used to generate data points.
+Available forumlae:
+
+* `interval` - The height of each point represents how long it has been
+  since the previous post.
+* `perday` - Each point represents a day; the height represents how
+  many posts were made that day.
+* `permonth` - Each point represents a month; the height represents how
+  many posts were made that month.
+* `peryear` - Each point represents a day; the height represents how
+  many posts were made that year.
+
+The `time` parameter has a default value of "ctime", since forumae use
+the creation times of pages by default. If you instead want
+them to use the modification times of pages, set it to "mtime".
+
+To change the color used to draw the sparkline, use the `color` parameter.
+For example, "color=red".