feat($compile): add commitizen wizard for easy commit message creation

Mimic the RxJs commit wizard for use with rxjs-docs. The rxjs-github-bot requires a certain format
for git messages. The commitizen and cs-conventional-changelog modules help make that a breeze.

No breaking changes. Just an added feature.

Author: Jennifer Luker

package.json

@@ -2,6 +2,11 @@
   "name": "rxjs-docs",
   "version": "0.0.0",
   "license": "MIT",
+  "config": {
+    "commitizen": {
+      "path": "cz-conventional-changelog"
+    }
+  },
   "scripts": {
     "ng": "ng",
     "start": "ng serve",