chore: branding usage of generate command (#10068)

- s/Gitea/Forgejo/ for the 'generate' subcommand.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10068
Reviewed-by: Lucas <sclu1034@noreply.codeberg.org>
Co-authored-by: Robert Wolff <mahlzahn@posteo.de>
Co-committed-by: Robert Wolff <mahlzahn@posteo.de>

cmd/generate.go

@@ -19,7 +19,7 @@ import (
 func cmdGenerate() *cli.Command {
 	return &cli.Command{
 		Name:  "generate",
-		Usage: "Generate Gitea's secrets/keys/tokens",
+		Usage: "Generate Forgejo's secrets/keys/tokens",
 		Commands: []*cli.Command{
 			subcmdSecret(),
 		},