Propose the "Custom Tooling and Dogfooding" DA handbook section for DX

Context

We wrote https://handbook.gitlab.com/handbook/engineering/infrastructure-platforms/developer-experience/development-analytics/#custom-tooling-and-dogfooding for DA initially, but I feel like this is applicable to Developer Experience as a whole.

Proposal

Move this section from https://handbook.gitlab.com/handbook/engineering/infrastructure-platforms/developer-experience/development-analytics to https://handbook.gitlab.com/handbook/engineering/infrastructure-platforms/developer-experience.