feat: support doctoc (nvim-lua#489)

* feat: support doctoc

* doc: shorten description

---------

Co-authored-by: Steven Arcangeli <[email protected]>

Author: KevinNitroG

lua/conform/formatters/doctoc.lua

@@ -0,0 +1,12 @@
+---@type conform.FileFormatterConfig
+return {
+  meta = {
+    url = "https://github.com/thlorenz/doctoc",
+    description = "Generates table of contents for markdown files inside local git repository.",
+  },
+  command = "doctoc",
+  stdin = false,
+  args = {
+    "$FILENAME",
+  },
+}