doc: generate vim docs

doc/telescope-git-grep.txt

@@ -171,6 +171,17 @@ The Garden file <garden.yaml> can be used to run lint checks using Garden
     garden check
 <
 
+The documentation is generated using panvimdoc
+<https://github.com/kdheepak/panvimdoc.git>.
+
+>bash
+    garden setup  # one-time setup
+    garden doc
+<
+
+Use `garden fmt` to apply code formatting using stylua
+<https://github.com/JohnnyMorganz/StyLua>.
+
 The github repository <https://github.com/davvid/telescope-git-grep.nvim> is a
 mirror of the main repository on gitlab
 <https://gitlab.com/davvid/telescope-git-grep.nvim> where you can file issues