-* `rcs_getchange` is passed a change id (as returned from rcs_recentchanges)
- and a partially filled out HTML::Template and fills out the remainer of the
- template. So if a template is used that includes diffs, it will need to run
- some expensive diffing operation, wikis with less resources can use a
- template that doesn't include diffs and avoid that overhead.
+* To add diffs, another plugin can add a pagetemplate hook that calls
+ a `rcs_diff`. (optional)