Document the heretofore missing joinClass option in WebGUI::Search.

docs/changelog/7.x.x.txt

@@ -1,6 +1,7 @@
 7.5.19
  - fixed: unable to purge trash
  - fixed: EMS not displaying all users with a badge
+ - fixed: WebGUI::Search - joinClass not documented
 
 7.5.18
  - fixed: Collateral Image Manager broken in Firefox 3

lib/WebGUI/Search.pm

@@ -324,6 +324,12 @@ This rule adds an additional where clause to the search.
 
  where => 'className NOT LIKE "WebGUI::Asset::Wobject%"'
 
+=head4 joinClass
+
+This is an array reference of asset classes.  Each asset class will be queried via its
+definition method to see what tables should be joined to the assetData table.  Only the
+most recent revisions of data will be added to the search.
+
 =head4 join
 
 This rule allows for an array reference of table join clauses.