Added docs as asciidoctor with cross platform support. (#5733)

* Added docs as asciidoctor with cross platform support.

* Fixed release script with new doc building mechanism.

doc/api/toolbar.adoc

@@ -0,0 +1,49 @@
+== Toolbar controller
+src/node/utils/toolbar.js
+
+=== button(opts)
+ * {Object} `opts`
+   * `command` - this command fill be fired on the editbar on click
+   * `localizationId` - will be set as `data-l10-id`
+   * `class` - here you can add additional classes to the button
+
+Returns: {Button}
+
+Example:
+
+[source, javascript]
+----
+var orderedlist = toolbar.button({
+  command: "insertorderedlist",
+  localizationId: "pad.toolbar.ol.title",
+  class: "buttonicon buttonicon-insertorderedlist"
+})
+----
+
+You can also create buttons with text:
+
+[source, javascript]
+----
+var myButton = toolbar.button({
+  command: "myButton",
+  localizationId: "myPlugin.toolbar.myButton",
+  class: "buttontext"
+})
+----
+
+=== selectButton(opts)
+ * {Object} `opts`
+   * `id` - id of the menu item
+   * `selectId` - id of the select element
+   * `command` - this command fill be fired on the editbar on change
+
+Returns: {SelectButton}
+
+=== SelectButton.addOption(value, text, attributes)
+ * {String} value - The value of this option
+ * {String} text - the label text used for this option
+ * {Object} attributes - any additional html attributes go here (e.g. `data-l10n-id`)
+
+=== registerButton(name, item)
+  * {String} name - used to reference the item in the toolbar config in settings.json
+  * {Button|SelectButton} item - the button to add