[examples][frameworks] Add missing examples and add a test to ensure every framework has an example (#4372)

* Add test to frameworks

* Add example for Docusaurus v2

* Add example for ionic-angular

* Update READMEs

* Use existing versions

* Reset yarn.lock

* Add schema validation and add missing Scully.io logo

examples/ionic-angular/src/zone-flags.ts

@@ -0,0 +1,5 @@
+/**
+ * Prevents Angular change detection from
+ * running with certain Web Component callbacks
+ */
+(window as any).__Zone_disable_customElements = true;