runtime(doc): add back help tag "pi_netrw.txt"

closes: #16974

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/pi_netrw.txt b/runtime/doc/pi_netrw.txt
index f6cc0dd..1189b37 100644
--- a/runtime/doc/pi_netrw.txt
+++ b/runtime/doc/pi_netrw.txt
@@ -1,4 +1,4 @@
-*netrw.txt*
+*netrw.txt*	*pi_netrw.txt*
 
 	    ------------------------------------------------
 	    NETRW REFERENCE MANUAL    by Charles E. Campbell