Add Analog Encoder Interface docs to the docs page

[mohamed-dek1]

Context

Related Issues / PRs: (To do: list all related issues)

• Replace the AEI circuit block diagram with the source SVG file AMDC-Hardware#276
• Release Rev A of the Analog Encoder Interface PCB design AMDC-Hardware#277
• Add doc files and REVXXXA folder AMDC-Hardware#273

We're working on releasing a revision for our new Analog Encoder Interface board. Once it's released, the docs for that page will be in the release folder and we want to move that to the AMDC docs page.

Approach

Close this issue by creating a PR that moves the aei docs to the AMDC docs page.