docs: extensions (#1258)

* docs: process docs to include UX Stories requirement

* docs: include note regarding different environments

* Services init

* Remove unused canny logos

* docs: add ModalService diagram

* docs: GIF of notification

* docs: add ui-services page

* docs: simplify ui services call out in the general services docs

* docs: tips and tricks for UI services

* docs: moar pages

* docs: dialog gif

* docs: services in summary/sidebar

* docs: gif examples at top of dialog and notification pages

* docs: add UIModal gif

* docs: details for Dialog Service

* docs: include usage information for ui modal service

* docs: detailed information about our UI Notification Service

* docs: services diagram

* docs: remove unused links

* docs: services example and image

* docs: stubbing extension pages

* docs: UX Stories --> User Cases

* chore: eslint fix

* docs: extensions overview + diagram

* docs: update extensions in sidebar

* docs: extension skeleton and registration info

* docs: copy of maintained extensions table partial in the extensions folder

* docs: swap out old extensions structure for new

platform/core/src/services/UIDialogService/index.js

@@ -16,7 +16,7 @@
  * @property {ReactElement|HTMLElement} content The dialog content.
  * @property {Object} contentProps The dialog content props.
  * @property {boolean} [isDraggable=true] Controls if dialog content is draggable or not.
- *  @property {boolean} [showOverlay=false] Controls dialog overlay.
+ * @property {boolean} [showOverlay=false] Controls dialog overlay.
  * @property {ElementPosition} defaultPosition Specifies the `x` and `y` that the dragged item should start at.
  * @property {ElementPosition} position If this property is present, the item becomes 'controlled' and is not responsive to user input.
  * @property {Function} onStart Called when dragging starts. If `false` is returned any handler, the action will cancel.