Get ansible-collection-atmosphere running in a internal environment.

Change the DNS suffix and ACME server. Both with the goal to get in this ansible-collection-atmosphere
running in internal environments.

Sem-Ver: feature
Change-Id: I43cf67ba32785c8e3f69e24f55bdc9d5ec22b75d
diff --git a/doc/source/user/quickstart.rst b/doc/source/user/quickstart.rst
index 1cf50ec..01f0a15 100644
--- a/doc/source/user/quickstart.rst
+++ b/doc/source/user/quickstart.rst
@@ -56,6 +56,15 @@
 ``ATMOSPHERE_USERNAME``
   The username what is used to login into the instances (defaults to ``ubuntu``).
 
+``ATMOSPHERE_DNS_SUFFIX_NAME``
+  The DNS domainname that is used for the API and Horizon. (defaults
+  to ``nip.io``).
+
+``ATMOSPHERE_ACME_SERVER``
+  The ACME server, currenly this is from Letsencrypt, with
+  StepCA from smallstep it is possible to run a internal ACME server.
+  The CA of that ACME server should be present in the instance image.
+
 Once you're ready to get started, you can run the following command to build
 the Heat stack and ::