Add ember-router-scroll to have correct scroll behavior ala static sites

Author: kategengler

package.json

@@ -98,6 +98,7 @@
     "ember-qunit": "^6.2.0",
     "ember-resolver": "^10.0.0",
     "ember-rfc176-data": "^0.3.17",
+    "ember-router-scroll": "^4.1.2",
     "ember-showdown-shiki": "^1.2.1",
     "ember-sinon": "^4.1.1",
     "ember-source": "~4.12.0",