Describe Babel solution to make fix IE11

Better tip for jhipster/generator-jhipster#10184 issue describing full solution in order to use Babel to make IE11 correctly working with JHipster generated applications.

Author: anthony-o

tips/028_tip_ie_support.md

@@ -8,7 +8,7 @@ lastmod: 2019-03-05T18:20:00-00:00
 
 # Provide Internet Explorer support
 
-**Tip submitted by [@wmarques](https://github.com/wmarques)**
+**Tip submitted by [@wmarques](https://github.com/wmarques)** & [@anthony-o](https://github.com/anthony-o)
 
 JHipster supports only evergreen browsers.
 However you can still easily support some older browsers like Internet Explorer.
@@ -19,3 +19,63 @@ In order to do that you have to:
 2. Then you have two options:
    1. Add the correct polyfills from 'core-js', if you don't know which one you should use, check the Angular CLI project and their polyfills.
    2. Or use babel + [Babel preset-env](https://babeljs.io/docs/en/babel-preset-env#usebuiltins) to automatically import the correct core-js polyfills based on a browserslist file.
+
+## Full tip using Babel
+
+First, add those `package.json` dependencies: `@babel/core`, `@babel/preset-env` and `babel-loader`. Example with `yarn`:
+```bash
+yarn add @babel/core @babel/preset-env babel-loader --exact --dev
+```
+(tested with the following versions for a working IE11 version on a JHipster v6.3.1 generated application:
+```json
+    "@babel/core": "7.6.4",
+    "@babel/preset-env": "7.6.3",
+    "babel-loader": "8.0.6",
+```
+)
+
+Now add the following lines at the top of `src/main/webapp/app/polyfills.ts`:
+```ts
+import 'core-js/stable';
+import 'regenerator-runtime/runtime';
+```
+
+In `webpack/webpack.common.js`, after
+```js
+            {
+                test: /manifest.webapp$/,
+                loader: 'file-loader',
+                options: {
+                    name: 'manifest.webapp'
+                }
+            },
+```
+add the following lines:
+```js
+            {
+                test: /\.js/,
+                use: {
+                  loader: 'babel-loader',
+                  options: {
+                    "presets": [
+                      [
+                        "@babel/preset-env",
+                        {
+                          "targets": {
+                            "firefox": "60",
+                            "ie": "11"
+                          },
+                          "useBuiltIns": "entry",
+                          "corejs": 3
+                        }
+                      ]
+                    ]
+                  }
+                },
+                exclude: /@babel(?:\/|\\{1,2})runtime|core-js/,
+              },
+```
+
+And finally, change `target` to `es5` in `tsconfig.json` & `tsconfig-aot.json`.
+
+See this [GitHub issue](https://github.com/jhipster/generator-jhipster/issues/10184#issuecomment-541650501) & [this SO answer](https://stackoverflow.com/a/58377002/535203) for more details.