chore(CI): fix "auto-update" Jenkins job

The job is currently failing, because the Node.js version used in not compatible with some of our
dependencies (e.g. Protractor).
The added `jenkins.sh` script is going to be executed by
https://ci.angularjs.org/job/angular-phonecat%20auto-update/.

Author: gkalpak

scripts/private/README.md

@@ -27,6 +27,14 @@ gh-pages branch on GitHub.
 git push origin gh-pages
 ```
 
+### Auto-updating Demo Pages from CI
+
+There is a Jenkins job that runs periodically and executes `jenkins.sh`.
+
+- **jenkins.sh**: This script will set the Node.js version to 4.x (using `nvm`), will run all the
+  tests (using `test-all.sh`) and update the demo pages (using `update-gh-pages.sh`).
+  (You shouldn't need to run this script manually.)
+
 ## Pushing to GitHub
 
 Each step in the tutorial is one commit in the git repository. Each step is also identified by a git 

scripts/private/jenkins.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# Install nvm for this shell
+source ~/.nvm/nvm.sh
+
+# Use Node.js v4.x
+nvm install 4
+
+# Run all tests
+test-all.sh
+
+# Publish steps on gh-pages
+update-gh-pages.sh