增加对于生成的导出变量的记录。

src/material-2-scheme.ts

@@ -31,4 +31,7 @@ export type MaterialDesign2SchemeSource = {
 export type MaterialDesign2SchemeStorage = {
   source?: MaterialDesign2SchemeSource;
   scheme?: MaterialDesign2Scheme;
+  cssVariables?: string;
+  scssVariables?: string;
+  jsVariables?: string;
 };