Update docs with correct links and SQLFluff install/use

[mddilley]

Associated issues

None. I copied the SQLFluff instructions 100% from https://github.com/cityofaustin/atd-moped/pull/1273 so h/t @frankhereford 🙏

Testing

URL to test:

n/a

Steps to test:

1. Please read and test the new link to our Moped Hasura docs.

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Ship list

• [x] Code reviewed
• [x] Product manager approved
• [x] Product manager checked DB view dependencies ~- [ ] Product manager added to QA test script if applicable~

[mddilley]

thanks, y'all! @roseeichelmann i only updated the links since the old one didn't go anywhere