With this move we don't need the existing separate `edx-platform
Technical` sphinx project. In the future we can remove it and just
redirect to the content in this project but I won't be doing that as a
part of this change because that involves adding redirects over there to
the new content and I'm not yet done organizing the destination.
The docs in the `guide` project might move around as we make the project
follow diataxis more closely.