Modify the Case Study name to represent content

The case studies in the Security Guide are all provided with
a basic chapter title of "Case Study". There's no clarity as
to which chapter they represent. For readability and usability
this should be updated so that both the index and document
content are accurate.

Change-Id: Id27f8512c26189ce9e2edbf6f605692e581bcddc
Closes-Bug: 1248918
Added Tenant-Create step to Create Base Networks

As reported to Launchpad, the creation of the base networks
document expects the user to create one or more initial tenants.
Whilst this has been done in prior steps, it's not clear, or
obvious how to do it. I've added a basic one-liner and linked
to relevant supporting documents in the install-guide.

Changes also fix a minor typo and append the "--tenant-id"
parameter to the user input sections where required.

Change-Id: I8ef3d3c69a5b10a9a4906f4249da1605f9a01e4c
backport: havana
Closes-Bug: 1261165
Merge "Added Tenant-Create step to Create Base Networks"
Merge "Modify the Case Study name to represent content"