add installation & usage section to each sub package README

Author: etpinard

tasks/sync_packages.js

@@ -68,6 +68,21 @@ packagesSpecs.forEach(function(d) {
             '',
             'For more info on plotly.js, go to https://github.com/plotly/plotly.js',
             '',
+            '## Installation',
+            '',
+            '```',
+            'npm install ' + d.name,
+            '```',
+            '## Usage',
+            '',
+            '```js',
+            '// ES6 module',
+            'import Plotly from \'' + d.name + '\';',
+            '',
+            '// CommonJS',
+            'var Plotly = require(\'' + d.name + '\');',
+            '```',
+            '',
             '## Copyright and license',
             '',
             'Code and documentation copyright 2018 Plotly, Inc.',