chore(lint): various changes to appease revive

- Add `package` comments
- Rename `opts` to `_` where unused

internal/display/faint.go

@@ -1,3 +1,5 @@
+// Package display implement functions pertaining to writing formatted
+// cheatsheet content to stdout, or alternatively the system pager.
 package display
 
 import (
@@ -6,7 +8,8 @@ import (
 	"github.com/cheat/cheat/internal/config"
 )
 
-// Faint returns an faint string
+// Faint returns a faintly-colored string that's used to de-prioritize text
+// written to stdout
 func Faint(str string, conf config.Config) string {
 	// make `str` faint only if colorization has been requested
 	if conf.Colorize {