docs(setup): instructs to delete non-essential files (#3079)

Author: wardbell

public/docs/_examples/setup/ts/non-essential-files.txt

@@ -0,0 +1,13 @@
+.git
+.gitignore
+.travis.yml
+*.spec*.ts
+CHANGELOG.md
+e2e
+favicon.ico
+karma.conf.js
+karma-test-shim.js
+LICENSE
+non-essential-files.txt
+protractor.config.js
+README.md

public/docs/ts/latest/guide/setup-systemjs-anatomy.jade

@@ -90,6 +90,15 @@ table(width="100%")
       :marked
         Script to run <a href="https://karma-runner.github.io/1.0/index.html" target="_blank" title="Karma unit test runner">karma</a>
         with SystemJS as described in the [Testing](testing.html) guide.
+  tr
+    td <code>non-essential-files.txt</code>
+    td
+      :marked
+        A list of files that you can delete if you want to purge your setup of the
+        original QuickStart Seed testing and git maintainence artifacts.
+        See instructions in the optional 
+        [_Deleting non-essential files_](setup.html#non-essential "Setup: Deleting non-essential files") section.
+        *Do this only in the beginning to avoid accidentally deleting your own tests and git setup!*
   tr
     td <code>LICENSE</code>
     td

public/docs/ts/latest/guide/setup.jade

@@ -64,7 +64,36 @@ code-example(language="sh" class="code-shell").
   :marked
     `npm start` fails in _Bash for Windows_ which does not support networking to servers as of January, 2017.
 
-.l-main-section#seed
+a#non-essential
+.l-main-section
+:marked
+  ## Delete _non-essential_ files (optional)
+
+  You can quickly delete the _non-essential_ files that concern testing and QuickStart repository maintenance
+  (***including all git-related artifacts*** such as the `.git` folder and `.gitignore`!).
+  
+.alert.is-important
+  :marked
+     Do this only in the beginning to avoid accidentally deleting your own tests and git setup!
+
+:marked
+  Open a terminal window in the project folder and enter the following commands for your environment:
+
+  ### OS/X (bash)
+code-example(language="sh" class="code-shell").
+  xargs -a non-essential-files.txt rm -rf
+  rm app/*.spec*.ts
+  rm non-essential-files.txt
+
+:marked
+  ### Windows
+code-example(language="sh" class="code-shell").
+    for /f %i in (non-essential-files.txt) do del %i /F /S /Q
+    rd .git /s /q
+    rd e2e /s /q
+
+a#seed
+.l-main-section
 :marked
   ## What's in the QuickStart seed?