Use modern compiler for css processing in vite (to remove SASS 2.0.0 warnings on deprecated JS API usage); (#180)

Resolve some of SASS deprecation warnings;
Add note to readme about icons generation

vite.config.ts

@@ -37,6 +37,13 @@ export default defineConfig({
   define: {
     global: "window",
   },
+  css: {
+    preprocessorOptions: {
+      scss: {
+        api: "modern-compiler",
+      },
+    },
+  },
   envPrefix: ["TAURI_", "VITE_"],
   plugins: [
     ViteYaml(),