[ACA-1889] Split Extending section into separate files (#784)

* [ACA-1889] Split Extending section into separate files

* [ACA-1889] Split Extending section into separate files

* [ACA-1889] Added recent changes and then deleted extending.md

* [ACA-1889] Added Tutorials section

docs/extending/routes.md

@@ -0,0 +1,80 @@
+---
+---
+
+# Routes
+
+To create a new route, populate the `routes` section with the corresponding entries.
+
+```json
+{
+  "$schema": "../../../extension.schema.json",
+  "$version": "1.0.0",
+  "$name": "plugin1",
+
+  "routes": [
+    {
+      "id": "plugin1.routes.bin",
+      "path": "ext/bin",
+      "layout": "app.layout.main",
+      "component": "your.component.id"
+    }
+  ]
+}
+```
+
+## Route properties
+
+| Name          | Description                                                                            |
+| ------------- | -------------------------------------------------------------------------------------- |
+| **id**        | Unique identifier.                                                                     |
+| **path**      | Runtime path of the route.                                                             |
+| **component** | The main [component](/extending/components) to use for the route.                                |
+| layout        | The layout [component](/extending/components) to use for the route.                              |
+| auth          | List of [authentication guards](/extending/routes#authentication-guards). Defaults to `[ "app.auth" ]`. |
+| data          | Custom property bag to carry with the route.                                           |
+
+Use the `app.layout.main` value for the `layout` property to get the default application layout,
+with header, navigation sidebar and main content area.
+You can register any component to back the `app.layout.main` value.
+
+<p class="tip">
+By default, the `app.layout.main` is used if you do not specify any custom values.
+Use `blank` if you want your route component take the whole page.
+</p>
+
+You can define the full route schema like in the next example:
+
+```json
+{
+  "$schema": "../../../extension.schema.json",
+  "$version": "1.0.0",
+  "$name": "plugin1",
+
+  "routes": [
+    {
+      "id": "plugin1.routes.bin",
+      "path": "ext/bin",
+      "component": "your.component.id",
+      "layout": "app.layout.main",
+      "auth": ["app.auth"],
+      "data": {
+        "title": "Custom Trashcan"
+      }
+    }
+  ]
+}
+```
+
+All application routes require at least one authentication guard.
+Defaults to the `['app.auth']` value.
+
+## Authentication Guards
+
+Below is the list of the authentication guards main application registers on startup.
+
+| Key      | Type         | Description                                                               |
+| -------- | ------------ | ------------------------------------------------------------------------- |
+| app.auth | AuthGuardEcm | ADF guard, validates ACS authentication and redirects to Login if needed. |
+
+You can refer those guards from within your custom extensions,
+or [register](/extending/registration) your custom implementations.