runtime(doc): document gitrebase filetype

closes: #16883

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/filetype.txt b/runtime/doc/filetype.txt
index 8a7f0c5..ac8d8f8 100644
--- a/runtime/doc/filetype.txt
+++ b/runtime/doc/filetype.txt
@@ -1,4 +1,4 @@
-*filetype.txt*	For Vim version 9.1.  Last change: 2025 Mar 10
+*filetype.txt*	For Vim version 9.1.  Last change: 2025 Mar 13
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -640,6 +640,24 @@
 in the preview window.  It is equivalent to calling "git diff --cached" plus
 any arguments given to the command.
 
+GIT REBASE						*ft-gitrebase-plugin*
+
+The gitrebase filetype defines the following buffer-local commands, to help
+with interactive `git rebase`: >
+
+	:Drop   " to discard this commit
+	:Edit   " to stop for editing this commit
+	:Fixup  " to squash (but discard the message) into the previous one
+	:Pick   " to pick this commit (the cursor is on)
+	:Reword " to pick this commit, but change the commit message
+	:Squash " to squash this commit into the previous one
+
+In addition, the following comamnd can be used to cycle between the different
+possibilities: >
+
+	:Cycle  " to cycle between the previous commands
+<
+For details, see `git-rebase --help`.
 
 GO							*ft-go-plugin*
 
diff --git a/runtime/doc/tags b/runtime/doc/tags
index 11ad3dd..a91b4af 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -7347,6 +7347,7 @@
 ft-fvwm-syntax	syntax.txt	/*ft-fvwm-syntax*
 ft-gdscript-plugin	filetype.txt	/*ft-gdscript-plugin*
 ft-gitcommit-plugin	filetype.txt	/*ft-gitcommit-plugin*
+ft-gitrebase-plugin	filetype.txt	/*ft-gitrebase-plugin*
 ft-go-plugin	filetype.txt	/*ft-go-plugin*
 ft-gprof-plugin	filetype.txt	/*ft-gprof-plugin*
 ft-groff-syntax	syntax.txt	/*ft-groff-syntax*