Update EE getting started URL to point to new location (#642)

docs/index.rst

@@ -31,7 +31,7 @@ Before you start using Ansible Builder, you should understand the following conc
 What are execution environments?
 ================================
 
-Refer to the `Getting started with Execution Environments guide <https://docs.ansible.com/ansible/devel/getting_started_ee/index.html>`_ for details.
+Refer to the `Getting started with Execution Environments guide <https://ansible.readthedocs.io/en/latest/getting_started_ee/index.html>`_ for details.
 
 Quickstart for Ansible Builder
 ==============================