added comment type for the FreeST language pt.2

Author: MiguelRoldao

runtime/plugins/comment/comment.lua

@@ -20,6 +20,7 @@ ft["dart"] = "// %s"
 ft["dockerfile"] = "# %s"
 ft["elm"] = "-- %s"
 ft["fish"] = "# %s"
+ft["freest"] = "-- %s"
 ft["gdscript"] = "# %s"
 ft["glsl"] = "// %s"
 ft["go"] = "// %s"