extension guide and example (#623)

* extension guide and example

* code and guide fixes

* update dependencies

tsconfig.json

@@ -30,6 +30,12 @@
       ],
       "@alfresco/adf-extensions/*": [
         "dist/@alfresco/adf-extensions/*"
+      ],
+      "my-extension": [
+        "dist/my-extension"
+      ],
+      "my-extension/*": [
+        "dist/my-extension/*"
       ]
     }
   },
@@ -39,4 +45,4 @@
   "angularCompilerOptions": {
     "preserveWhitespaces": false
   }
-}
+}