patch 9.1.1186: filetype: help files in git repos are not detected

Problem:  filetype: help files in git repos are not detected
Solution: detect */doc/*.txt files as help if they end with a help
          modeline, even if 'modeline' is off

Here's how I checked that this would still detect vim's own help files
correctly:

$ find . -type f -path '*/doc/*.txt' \
> -exec awk '{ } ENDFILE { print FILENAME ":" $0; }' '{}' + |
> grep -v 'vim:.*\<\(ft\|filetype\)=help\>'
./src/libvterm/doc/seqs.txt: 23    DECSM 42         = DECNRCM, national/multinational character

closes: #16817

Signed-off-by: David Mandelberg <david@mandelberg.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/todo.txt b/runtime/doc/todo.txt
index 9bdcfe0..cf9a82a 100644
--- a/runtime/doc/todo.txt
+++ b/runtime/doc/todo.txt
@@ -1,4 +1,4 @@
-*todo.txt*      For Vim version 9.1.  Last change: 2025 Feb 21
+*todo.txt*      For Vim version 9.1.  Last change: 2025 Mar 08
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -6276,5 +6276,4 @@
     are reflected in each Vim immediately.  Could work with local files but
     also over the internet.  See http://www.codingmonkeys.de/subethaedit/.
 
-vim:tw=78:sw=4:sts=4:ts=8:noet:ft=help:norl:
-vim: set fo+=n :
+vim:tw=78:sw=4:sts=4:ts=8:noet:ft=help:norl:fo+=n: