Pushing-Images-to-AWS - Update to include RHEL 7.6 within scope

Adding a few changes to make the content cover the RHEL use-case. For RHEL
7.6, the software collections python36 revision can be used to install the
awscli utility. Also removed reference to specifically using Fedora 29 for
the process as it isn't necessary. Just a system that is RHEL 7.6 or above,
and Fedora 29 or above.

_posts/2018-10-08-Pushing-Images-to-AWS.md

@@ -13,9 +13,8 @@ partition layout, and include cloud-init.
 
 ## Prerequisites
 
-We'll use [Fedora 29](https://getfedora.org/) as our OS of choice for running this. Run
-this in its own VM with at least 8 gigabytes of memory and 40 gigabytes of disk space.
-[Lorax](http://weldr.io/lorax/) makes some changes to the operating system its running on.
+Run this in its own VM with at least 8 gigabytes of memory and 40 gigabytes of disk space.
+[Lorax](https://weldr.io/lorax/) makes some changes to the operating system its running on.
 
 First install Composer:
 
@@ -39,9 +38,21 @@ If you're going to use [Cockpit](https://cockpit-project.org/) UI to drive Compo
 
 Install the [AWS client](https://aws.amazon.com/cli/) tooling:
 
+Fedora 29+
+
     $ sudo yum install python3-pip
     $ sudo pip3 install awscli
 
+RHEL 7.6+
+
+    $ sudo subscription-manager repos --enable rhel-server-rhscl-7-rpms
+    $ sudo yum install rh-python36-python-pip -y
+    $ sudo scl enable rh-python36 -- pip install awscli
+    $ scl enable rh-python36 bash
+
+Note, with RHEL 7.6 systems, any aws commands following will need to be issued within the
+scl enable wrapper.
+
 Make sure you have an *Access Key ID* configured in
 [AWS IAM account manager](https://aws.amazon.com/iam/) and use that info to configure
 the AWS command line client: