manager: Update ModuleCheck documentation.

The ModuleCheck XML documentation falsely
claims that the module's version number is returned.
This has not been the case since 14, since the version
number is not available anymore, but the documentation
was not changed at the time. It is now updated to
reflect this.

ASTERISK-30285 #close

Change-Id: Idde2d1205a11f2623fa1ddab192faa3dc4081e91

main/manager.c

@@ -1109,7 +1109,8 @@
 		</syntax>
 		<description>
 			<para>Checks if Asterisk module is loaded. Will return Success/Failure.
-			For success returns, the module revision number is included.</para>
+			An empty Version header is also returned (which doesn't contain
+			the module revision number).</para>
 		</description>
 		<see-also>
 			<ref type="manager">ModuleLoad</ref>