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

closes: #16974

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/Makefile b/runtime/doc/Makefile
index e278933..0f142a3 100644
--- a/runtime/doc/Makefile
+++ b/runtime/doc/Makefile
@@ -142,7 +142,9 @@
 	touch $@
 
 pi_netrw.txt: ../pack/dist/opt/netrw/doc/netrw.txt
-	cp ../pack/dist/opt/netrw/doc/netrw.txt $@
+	cp ../pack/dist/opt/netrw/doc/netrw.txt $@.tmp
+	sed -e '1s/\(.*\)/\0	*pi_netrw.txt*/' $@.tmp > $@ && \
+	rm -f $@.tmp
 
 vietnamese.txt:
 	touch $@
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
diff --git a/runtime/doc/tags b/runtime/doc/tags
index 2a4fc48..a02d07e 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -9522,6 +9522,7 @@
 pi_getscript.txt	pi_getscript.txt	/*pi_getscript.txt*
 pi_gzip.txt	pi_gzip.txt	/*pi_gzip.txt*
 pi_logipat.txt	pi_logipat.txt	/*pi_logipat.txt*
+pi_netrw.txt	pi_netrw.txt	/*pi_netrw.txt*
 pi_paren.txt	pi_paren.txt	/*pi_paren.txt*
 pi_spec.txt	pi_spec.txt	/*pi_spec.txt*
 pi_tar.txt	pi_tar.txt	/*pi_tar.txt*