Add support for middleman app

docs/web-support/middleman.md

@@ -0,0 +1,19 @@
+### Middleman
+
+Make sure you have `middleman-sprockets` in your `Gemfile`
+```ruby
+gem 'middleman-sprockets'
+gem 'apexcharts'
+```
+Don't forget to `bundle install`.
+
+Activate them in `config.rb`
+```ruby
+activate :sprockets
+activate :apexcharts
+```
+
+and then require it in your `source/javascripts/site.js`.
+```js
+//= require apexcharts
+```

lib/apex_charts/support/middleman.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class ApexCharts::Middleman < Middleman::Extension
+  def initialize(app, options_hash={}, &block)
+    super
+  end
+
+  helpers ::ApexCharts::Helper
+end
+
+::Middleman::Extensions.register(:apexcharts, ApexCharts::Middleman)

lib/apexcharts.rb

@@ -3,3 +3,4 @@
 require 'apex_charts/helper'
 require 'apex_charts/support/rails' if defined? Rails
 require 'apex_charts/support/sinatra' if defined? Sinatra
+require 'apex_charts/support/middleman' if defined? Middleman::Extension