Adding docs for importmaps

Author: fzf

docs/web-support/rails.md

@@ -19,3 +19,45 @@ window.ApexCharts = require("apexcharts") // expose to window
 import ApexCharts from 'apexcharts'
 window.ApexCharts = ApexCharts
 ```
+
+Or, if you use `importmaps', you can:
+
+Download to local vendor directory (optional but recommended)
+
+```bash
+$ wget -O vendor/javascript/apexcharts.esm.js https://ga.jspm.io/npm:apexcharts@latest/dist/apexcharts.esm.js`
+```
+
+Pin "apexcharts" in `config/importmap.rb` to local esm file (if you do No. 1):
+
+```ruby
+pin "apexcharts", to: "apexcharts.esm.js"`
+```
+
+or, to CDN URL
+
+```ruby
+pin "apexcharts", to: "https://ga.jspm.io/npm:apexcharts@latest/dist/apexcharts.esm.js"`
+```
+
+Import and assign to window in `app/javascript/application.js`
+
+```js
+import ApexCharts from "apexcharts"
+window.ApexCharts = ApexCharts
+```
+
+Use it with options `module: true`
+For example:
+
+```
+<% series = [{
+    name: "Desktops",
+    data: [10, 41, 35, 51, 49, 62, 69, 91, 148]
+  }]
+  options = {
+    module: true
+  }
+%>
+<%= line_chart(series, options) %>
+```