Support gleam module documentation comment ////

[inoas]

Example (global config):

	"better-comments.tags": [
		{
			"tag": "//",
			"color": "#ffaff3",
			"strikethrough": false,
			"underline": false,
			"backgroundColor": "transparent",
			"bold": true,
			"italic": true
		}
	]

This will however change it for all languages.
It would also be preferred to keep the regular comments colour inherited from the theme.

For module comments, see https://gleam.run/writing-gleam/documenting-the-project/