[SWAGGER] Make it consistent with reality

- Make the `UserSettings` definition an non-array, this is consistent
with the existing endpoints that uses this definition.
- Resolves #4179

routers/api/v1/swagger/user.go

@@ -46,5 +46,5 @@ type swaggerResponseUserHeatmapData struct {
 // swagger:response UserSettings
 type swaggerResponseUserSettings struct {
 	// in:body
-	Body []api.UserSettings `json:"body"`
+	Body api.UserSettings `json:"body"`
 }