[skip ci] docs: show how to use history mode in electron:build

Author: nklayman

docs/guide/commonIssues.md

@@ -6,18 +6,23 @@ sidebarDepth: 2
 
 ## Blank screen on builds, but works fine on serve
 
-This issue is likely caused when vue-router is operating in `history` mode. Disable history mode like so:
+This issue is likely caused when vue-router is operating in `history` mode. To fix this, add a `mounted` hook to the root Vue component:
 
 ```javascript
-// src/router.js or src/router/index.js
-// ...
-export default new Router({
-  mode: 'hash' // instead of "mode: 'history'"
-  // ...
-})
-// ...
+// src/main.js
+
+new Vue({
+  router,
+  render: h => h(App),
+  mounted() {
+    // Prevent blank screen in Electron builds
+    this.$router.push('/')
+  }
+}).$mount('#app')
 ```
 
+This will fix the Electron build issues, but won't affect web builds.
+
 ## `electron:serve` freezes on `Launching Electron...`
 
 Often this issue is caused when Vue Devtools fails to install. This may happen if Vue Devtools cannot be accessed in your location (eg. China). To fix this, you may have to disable Vue Devtools by removing the following lines from your `src/background.(js|ts)` file: