feat: add commitmsgfmt (#579)

* feat: add commitmsgfmt

formatters_by_ft = {
    ...
    gitcommit = {"commitmsgfmt"},
}

Signed-off-by: Javier Tia <[email protected]>

* doc: enforce consistent description format

---------

Signed-off-by: Javier Tia <[email protected]>
Co-authored-by: Steven Arcangeli <[email protected]>

Author: Javier Tia

lua/conform/formatters/commitmsgfmt.lua

@@ -0,0 +1,9 @@
+---@type conform.FileFormatterConfig
+return {
+  meta = {
+    url = "https://gitlab.com/mkjeldsen/commitmsgfmt",
+    description = "Formats commit messages better than fmt(1) and Vim.",
+  },
+  command = "commitmsgfmt",
+  stdin = true,
+}