runtime(doc): document gitcommit_summary_length

related: #19905

Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/runtime/doc/filetype.txt b/runtime/doc/filetype.txt
index 6a7fa3b5905ab2d5307a40aab106bb3aa26431d8..3aa41db21a536c8ca72ab29eb5877486fc9bb862 100644 (file)
--- a/runtime/doc/filetype.txt
+++ b/runtime/doc/filetype.txt
@@ -1,4 +1,4 @@
-*filetype.txt* For Vim version 9.2.  Last change: 2026 Mar 24
+*filetype.txt* For Vim version 9.2.  Last change: 2026 Apr 07
 
 
                  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -652,6 +652,13 @@ One command, :DiffGitCached, is provided to show a diff of the current commit
 in the preview window.  It is equivalent to calling "git diff --cached" plus
 any arguments given to the command.
 
+
+The length of the first line of the commit message used for
+syntax highlighting can be configured via `g:gitcommit_summary_length`.
+The default is 50.  Example: >
+
+        let g:gitcommit_summary_length = 70
+
 GIT REBASE                                             *ft-gitrebase-plugin*
 
 The gitrebase filetype defines the following buffer-local commands, to help