Visualization doc in internal docs is 404.

[GoDotDotDot]

Describe the bug When I looked at the internal development documentation, I found How to generate a visualization of this repository's development was missing.

Steps to reproduce (REQUIRED) Steps to reproduce the behavior, libraries used with version number, and/or any setup information to easily reproduce:

1. Go to https://github.com/MetaMask/metamask-extension/tree/develop/docs
2. Click on How to generate a visualization of this repository's development

Expected behavior A clear description of what you expected to happen.

Screenshots If applicable, add screenshots to help explain your problem.

Browser details (please complete the following information):

• OS: [e.g. OS X, Windows]
• Hardware Wallet: [e.g. Trezor Firmware version 1.8.3, Ledger Nano S Firmware version 1.6.0]
• Browser: [e.g. Chrome Version 79.0.3945.79 (Official Build) (64-bit), Firefox Browser 71.0 (64-bit)]
• MetaMask Version: [e.g. 5.0.2 - find it in Settings > About]

Additional context (Error Messages, etc.) Add any other context about the problem here.

[GoDotDotDot]

• How to live reload on local dependency changes
• How to add new networks to the Provider Menu
• How to port MetaMask to a new platform
• How to generate a visualization of this repository's development

Several of the above documents are also unavailable for viewing.