Documentation cleanup

Minor cleanups while looking through the current docs as part of gitlab-com/gl-infra/delivery#2143 (closed).

Commits are atomic and may make review easier.

general/deploy/auto-deploy-transition.md

-# Overview
-
-The [auto-deploy process overview](auto-deploy.md) provides details on the
-building pieces of the process, a schedule overview and answers a few frequently
-asked questions.
-
-Previous contents of this document were used to transition from the monthly deploy cadence to the new deploy system. For the most current information, 
-checkout the [Releases Handbook page](https://about.gitlab.com/handbook/engineering/releases/). 
-