Split exportExtensions into exportDefault and exportNamespace plugins… (#6920)

* Split exportExtensions into two plugins in babylon
* rename proposal-export-default to proposal-export-default-from
* rename proposal-export-namespace to proposal-export-namespace-from

packages/babel-plugin-syntax-export-default-from/README.md

@@ -0,0 +1,35 @@
+# @babel/plugin-syntax-export-default-from
+
+> Allow parsing of `export default from`.
+
+## Installation
+
+```sh
+npm install --save-dev @babel/plugin-syntax-export-default-from
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["@babel/plugin-syntax-export-default-from"]
+}
+```
+
+### Via CLI
+
+```sh
+babel --plugins @babel/plugin-syntax-export-default-from script.js
+```
+
+### Via Node API
+
+```javascript
+require("@babel/core").transform("code", {
+  plugins: ["@babel/plugin-syntax-export-default-from"]
+});
+```