Add missing 404 response to Swagger (#27038)

Most middleware throw a 404 in case something is not found e.g. a Repo
that is not existing. But most API endpoints don't include the 404
response in their documentation. This PR changes this.

routers/api/v1/repo/patch.go

@@ -45,6 +45,8 @@ func ApplyDiffPatch(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/FileResponse"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
 	apiOpts := web.GetForm(ctx).(*api.ApplyDiffPatchFileOptions)
 
 	opts := &files.ApplyDiffPatchOptions{