Docs Index is too wall-of-texty, loses Pyramid Introduction

[stevepiercy]

The Pyramid Introduction is lost in the wall of text, listed as the first page under Narrative Documentation. We have previously shuffled and re-shuffled sections around, but the constraint of the current Sphinx theme and its layout makes this difficult to solve. We also duplicate content that now exists on trypyramid.com that should not be here as we have already sold the user to use Pyramid.

We need to promote "Pyramid Introduction" to be more prominent on the main page, implementation TBD, possibly after I finish the new Pyramid Sphinx theme. TryPyramid.com already does this well on its home page:

Developers may dive in to Pyramid's narrative documentation,

[crooksey]

Should we also not (if changing this) redirect http://www.pylonsproject.org/ to trypyramid.com.

As if a new user was to google pyramid framework, they are taken to pylonsproject.org, we cannot assume all users have seen trypyramid.com

Then the documentation index could simply start from below Narrative Documentation (from http://docs.pylonsproject.org/projects/pyramid/en/latest/index.html):

Narrative Documentation

Narrative documentation in chapter form explaining how to use Pyramid.

Pyramid Introduction

[stevepiercy]

pylonsproject.org shall become the marketing website of the umbrella organization Pylons Project and provide a page for each of its projects. Example:
http://www.pocoo.org/projects/

Here's the proposed site structure.
Pylons/pylonsproject.org#7

[stevepiercy]

See #2634 and #2614