Lang string fixes for "Watchlist" help files (Bug 892959)

The lang strings for the watchlist needed to be
updated as there is no watchlist for groups and
journals. I also alphabetized the strings in the
help file for the inbox.

Change-Id: I61c959a2fe79081983832b6d0238acc3cb54d63e
Signed-off-by: Kristina D.C. Hoeppner <kristina@catalyst.net.nz>

htdocs/lang/en.utf8/help/forms/activityprefs.activity_watchlist.html

 <!-- @license http://www.gnu.org/copyleft/gpl.html GNU GPL version 3 or later -->
 <!-- @copyright For copyright information on Mahara, please see the README file distributed with this software. -->
 <h3>Watchlist</h3>
-<p>Notification of activity on any artefact, page, group or journal that is on the watchlist.</p>
\ No newline at end of file
+<p>Notification of activity on any artefact or page that you are monitoring.</p>
\ No newline at end of file

htdocs/lang/en.utf8/help/sections/activitytypeselect.html

 <!-- @license http://www.gnu.org/copyleft/gpl.html GNU GPL version 3 or later -->
 <!-- @copyright For copyright information on Mahara, please see the README file distributed with this software. -->
 <h3>Activity type</h3>
-<p>Select from this drop-down menu the notification type you wish to view.</p>
-<p><strong>New forum post:</strong> notification of a new post to a forum topic you have subscribed to</p>
-<p><strong>Feedback:</strong> notification of any feedback or comments received on any pages, artefacts or journals within your ePortfolio</p>
-<p><strong>Group message:</strong> notification sent to group owners when new pages are submitted to a group</p>
-<p><strong>System message:</strong> automatically generated by the system or sent to you by one of the site administrators</p>
-<p><strong>Message from other users:</strong> sent to you directly from other users of the site</p>
-<p><strong>New page access:</strong> notification that you or one of your groups have been given access to a new or existing non-public page</p>
-<p><strong>Watchlist:</strong> notification of activity on any artefact, page, group or journal you are monitoring</p>
+<p>Select from this drop-down menu the notification type you wish to view. You may not be able to see all notification types depending on your permissions in the system.</p>
+<p><strong>Administration messages:</strong> Notifications to site and institution administrators.</p>
+<p><strong>Feedback:</strong> Notification of any feedback or comments received on any pages, artefacts or journals within your ePortfolio.</p>
+<p><strong>Group message:</strong> Notification sent to group owners when new pages are submitted to a group.</p>
+<p><strong>Institution message:</strong> Automatically generated by the system if you are a member of an institution or are about to be.</p>
+<p><strong>Message from other users:</strong> Sent to you directly from other users of the site.</p>
+<p><strong>New forum post:</strong> Notification of a new post to a forum topic you are subscribed to.</p>
+<p><strong>New page access:</strong> Notification that you or one of your groups have been given access to a new or existing page or collection.</p>
+<p><strong>System message:</strong> Automatically generated by the system or sent to you by one of the site administrators.</p>
+<p><strong>Watchlist:</strong> Notification of activity on any artefact or page that you are monitoring.</p>