Update the main storage reference page in Aztec docs

[critesjosh]

This page is currently the token tutorial for some reason, should be updated.

Current page: https://github.com/AztecProtocol/aztec-packages/blob/master/docs/docs/developers/contracts/references/storage/main.md

Previous page, maybe update to this? https://github.com/AztecProtocol/aztec-packages/blob/f1ebac68da6b453b13cf8b7ddbce36cb25b0255f/docs/docs/developers/contracts/syntax/storage/main.md