add contrib plugin page for the mailbox plugin

doc/plugins/contrib/mailbox.mdwn

@@ -0,0 +1,18 @@
+[[!template id=plugin name=mailbox author="[[DavidBremner]]"]]
+[[!tag type/format]]
+
+The `mailbox` plugin adds support to ikiwiki for 
+rendering mailbox file into a page displaying the mails
+in the mailbox. It supports mbox, maildir, and MH folders,
+does threading, and deals with MIME.
+
+One hitch I noticed was that it is not currently possible to treat a
+maildir or an MH directory as a page (i.e. just call it foo.mh and have it
+transformed to page foo). I'm not sure if this is possible and worthwhile
+to fix. It is certainly workable to use a [[!mailbox ]] directive.
+-- [[DavidBremner]]
+
+This plugin is not in ikiwiki yet, but can be downloaded
+from <http://pivot.cs.unb.ca/git/ikimailbox.git>
+
+

doc/todo/mbox.mdwn

@@ -3,7 +3,7 @@ I'd like to be able to drop an unmodified RFC2822 email message into ikiwiki, an
 > We're discussing doing just that (well, whole mailboxes, really) over in
 > [[comment_by_mail]] --[[Joey]]
 >> The 
->> [mailbox](http://pivot.cs.unb.ca/git/?p=ikimailbox.git;a=summary) 
+>> [[plugins/mailbox]]
 >> plugin is roughly feature complete at this point.  It can read mbox, maildir, and
 >> MH folders, does threading, and deals with MIME (now with 
 >> pagespec based sanity checking).  No doubt lots of things could be 
@@ -15,8 +15,4 @@ I'd like to be able to drop an unmodified RFC2822 email message into ikiwiki, an
 >>  It is certainly workable
 >>> to use a \[[!mailbox ]] directive. -- [[DavidBremner]]
 
-> Your gitweb doesn't tell me where I can git pull this from, which I'd
+[[done]]
-> like to do ... --[[Joey]]
-
->> Found it: <http://pivot.cs.unb.ca/git/ikimailbox.git> --[[Joey]]
-