app_sendtext: Remove references to removed applications.

Removes see-also references to applications that don't
exist anymore (removed in Asterisk 19),
so these dead links don't show up on the wiki.

ASTERISK-30347 #close

Change-Id: I9539bc30f57cd65aa4e2d5ce8185eafa09567909

apps/app_sendtext.c

@@ -139,8 +139,6 @@
 			</example>
 		</description>
 		<see-also>
-			<ref type="application">SendImage</ref>
-			<ref type="application">SendURL</ref>
 			<ref type="application">ReceiveText</ref>
 		</see-also>
 	</application>
@@ -182,8 +180,6 @@
 		</description>
 		<see-also>
 			<ref type="application">SendText</ref>
-			<ref type="application">SendImage</ref>
-			<ref type="application">SendURL</ref>
 		</see-also>
 	</application>
  ***/