manager: Remove documentation for nonexistent action.

The manager XML documentation documents a "FilterList"
action, but there is no such action. Therefore, this can
lead to confusion when people try to use a documented
action that does not, in fact, exist. This is removed
as the action never did exist in the past, nor would it
be trivial to add since we only store the regex_t
objects, so the filter list can't actually be provided
without storing that separately. Most likely, the
documentation was originally added (around version 10)
in anticipation of something that never happened.

ASTERISK-29917 #close

Change-Id: I846b16fd6f80a91d4ddc5d8a861b522d7c6f8f97

main/manager.c

@@ -1283,21 +1283,6 @@
 			this command can be used to create filters that may bypass
 			filters defined in manager.conf</para>
 		</description>
-		<see-also>
-			<ref type="manager">FilterList</ref>
-		</see-also>
-	</manager>
-	<manager name="FilterList" language="en_US">
-		<synopsis>
-			Show current event filters for this session
-		</synopsis>
-		<description>
-			<para>The filters displayed are for the current session.  Only those filters defined in
-                        manager.conf will be present upon starting a new session.</para>
-		</description>
-		<see-also>
-			<ref type="manager">Filter</ref>
-		</see-also>
 	</manager>
 	<manager name="BlindTransfer" language="en_US">
 		<synopsis>