help: make the keystrokes ^W^Y and ^W^V work again

The keystrokes are not listed, but should work like
they do in a normal, editable buffer.

This fixes https://savannah.gnu.org/bugs/?61274.

Bug existed since version 4.0, commit bc98dbca.

src/global.c

@@ -1442,8 +1442,8 @@ void shortcut_init(void)
 	add_to_sclist(MGOTOLINE, "^W", 0, to_para_begin, 0);
 	add_to_sclist(MGOTOLINE, "^O", 0, to_para_end, 0);
 #endif
-	add_to_sclist(MGOTOLINE, "^Y", 0, to_first_line, 0);
-	add_to_sclist(MGOTOLINE, "^V", 0, to_last_line, 0);
+	add_to_sclist(MGOTOLINE|MFINDINHELP, "^Y", 0, to_first_line, 0);
+	add_to_sclist(MGOTOLINE|MFINDINHELP, "^V", 0, to_last_line, 0);
 	/* Some people are used to having these keystrokes in the Search menu. */
 	add_to_sclist(MWHEREIS, "^Y", 0, to_first_line, 0);
 	add_to_sclist(MWHEREIS, "^V", 0, to_last_line, 0);