Review Brokerage Repo Readmes

[DerekMelchin]

Expected Behavior

The brokerage repo readmes (example) have up-to-date information and all links are functional

Actual Behavior

These brokerage repo readmes fall out-of-date over time. For example, one of the terminal outputs on the Coinbase repo includes brokerages that we don't even support anymore.

    $ lean live 'My Project'

    Select a brokerage:
    1. Paper Trading
    2. Interactive Brokers
    3. Tradier
    4. OANDA
    5. Bitfinex
    6. Coinbase Pro
    7. Binance
    8. Zerodha
    9. Samco
    10. Terminal Link
    11. Atreyu
    12. Trading Technologies
    13. Kraken
    14. FTX
    Enter an option: 

The Coinbase repo even includes steps in the deployment process that are no longer required. For example, the deployment wizard support existing holdings now, but the repo doesn't reflect this.

Moreover, the readmes have broken links. We should extend the automated link checker to scan the links on these brokerage/dataset repos.

Checklist

• [x] I have completely filled out this template
• [x] I have confirmed that this issue exists on the current master branch
• [x] I have confirmed that this is not a duplicate issue by searching issues

[DerekMelchin]

We can extend this to the DataSource repos too. All of these links

See Tutorials for a step by step guide for creating a new LEAN Data Source.

in those repos return a 404