Docs: Link from renderer narrative docs to example render_to_response call, and index the example.

More fully explain the 2 examples, one with render_to_response call
and one without.
Docs: renders.rst: Use punctuation to make sentence simpler.
Docs: renders.rst: Break sentence into two to simplify.
Docs: renders.rst: Make sentences short per IRC chat with committers.
Docs: renders.rst: Make sentences that everybody's happy with.
Merge branch 'doc_render_to_response2' of github.com:kpinc/pyramid into kpinc-doc_render_to_response2