Fix two documentation typos (#1248)

Author: fossil12

docs/backend.md

@@ -11,7 +11,7 @@ const path = require('path')
 
 module.exports = {
   dev: {
-    / Paths
+    // Paths
     assetsSubDirectory: 'static',
     assetsPublicPath: '/',
     proxyTable: {},

docs/structure.md

@@ -21,8 +21,8 @@
 │   │   ├── eslintrc            # config file for eslint with extra settings only for unit tests
 │   │   ├── index.js            # test build entry file
 │   │   ├── jest.conf.js        # Config file when using Jest for unit tests
-│   │   └── karma.conf.js       # test runner config file when using Karma for unit tests
-│   │   ├── setup.js            # file that runs before Jest runs your unit tests
+│   │   ├── karma.conf.js       # test runner config file when using Karma for unit tests
+│   │   └── setup.js            # file that runs before Jest runs your unit tests
 │   └── e2e/                    # e2e tests
 │   │   ├── specs/              # test spec files
 │   │   ├── custom-assertions/  # custom assertions for e2e tests