[Docs] Add Ansible task example

Add Ansible task example to show how to install nvm and update it.

Ansible is a systems administration tool.
See https://github.com/ansible/ansible

My personal experience of `nvm` is that installing via Ansible is good, and that a good example can help. This example took me about an hour to learn, so I'm hoping to save other people some time. This example is somewhat different than any others that I found on the web. There may be a better way to write it, and if so, please improve it.

README.md

@@ -6,6 +6,7 @@
 
 - [Installation](#installation)
   - [Install script](#install-script)
+    - [Ansible](#ansible)
   - [Verify installation](#verify-installation)
   - [Important Notes](#important-notes)
   - [Git install](#git-install)
@@ -91,6 +92,17 @@ If the above doesn't fix the problem, open your `.bash_profile` and add the foll
 
 - For more information about this issue and possible workarounds, please [refer here](https://github.com/creationix/nvm/issues/576)
 
+#### Ansible
+ You can use a task:
+
+```
+- name: nvm
+  shell: >
+    curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.11/install.sh | bash
+  args:
+    creates: "{{ ansible_env.HOME }}/.nvm/nvm.sh"
+```
+
 ### Verify installation
 
 To verify that nvm has been installed, do: