[WIP] Modularize the Intro to MTA guide

[mpershina]

This PR is set to track modularization efforts for the Introduction to the Migration Toolkit for Applications.

[mpershina]

This module will be deleted, the info is moved to assemblies/mta-intro

[mpershina]

Please, see the suggested repo structure first. Note that this first PR is a experimental one and the changes are not firm yet and are subject to further modifications.

For now, I have only created the assemblies directory and other sub-directories, such as mta-intro sub-directory under topics and mta-intro as a sub-directory for assemblies. I haven't renamed topics and docs yet as I wanted to ask if we want it right now or after some release? This renaming will brake the links, which I can definitely fix, but I'd better as you both about that :-) So, what do you think, @raoradhika and @anarnold97?

The same applies to moving images out of topics to the same level as assemblies, docs, and topics.

Another question of mine: Since the inclusive language statement is supposed to be in the footer after some initiative, shall I go ahead and remove the making-open-source-more-inclusive.adoc module from all of MTA titles? This module has been removed from all RHEL docs some time ago as well.

P.S.: I ran the ccutil, and the title builds just fine for me.