[C4 Analysis] Add warnings in LSP0, LSP6 & LSP17

[b00ste]

What does this PR introduce?

In this PR I add warnings and best practices for the LSP0, LSP6 & LSP17 documentation.

LSP0ERC725Account

Fallback

• Warning that the 0x00000000 function selector is the only one that returns.

LSP6KeyManager

Permissions

• Risk when using a single controller with SUPER permissions.
• Risk when granting permissions to 3rd parties.

Relay Call

• Risk of Relay Services to send your transaction with log gas price.
• Risk of Relay Services to front-run your transaction .

LSP17ContractExtension

• Risk of loosing native tokens when sending msg.value on an extension call.
• Risk to metamoprhic contracts. Tornado Cash Governance Hack

[Hugoo]

Task linked: DEV-7972 Put content from Code4Rena Analysis reports in docs

[CJ42]

Let's discuss where these should go. They might fit better maybe in the "Contracts" section instead of the "Standards" section (which is more for the High Level concepts of each standard)