💻 Document Election Customization for Specification

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Suggestion

There is missing information for the Specification when it comes to how an Election can be customized. There are a several different areas that should be discussed but the primary areas to discuss are the (1) `Manifest` and how ballots are coded, (2) how extended_data works for the context of the election, (3) how enabling overvotes changes the election.

### Possible Implementation

This will be a Latex document that is generated as a pdf should be added to the release 1.0 directly.

### Anything else?

_No response_