[Docs] Document URL parameters

[alfetopito]

Summary

We used to have documentation for URL parameters but it got lost at some point.

Add documentation for all supported parameters, which are:

• sellAmount
• buyAmount
• receiver

Also mention the context on how they are loaded.

Namely, on SWAP, either sellAmount or buyAmount values are expected. When both are set, sellAmount is used. While on LIMIT`, both are accepted and this in turn is used to set the limit price.

[fleupold]

We should also document the different ways to specify the pair and chain (Symbol vs addresses)

Not the right repo I know, but could we also make appData pass-able?

[alfetopito]

Turns out we do have it already, but it's not yet published for some reason https://github.com/cowprotocol/docs/blob/ab8d7fbe72489af9f4b0f6d2cf0c3cd35be6c76a/docs/cow-protocol/tutorials/cow-swap/custom-links.md

[alfetopito]

Not the right repo I know, but could we also make appData pass-able?

You mean to document the appData in the docs? Or to allow the appData to be set from the url?

[fleupold]

Or to allow the appData to be set from the url?

This ☝️

[alfetopito]

Or to allow the appData to be set from the url?

This ☝️

https://github.com/cowprotocol/cowswap/issues/4107

[alfetopito]

Addressed on https://github.com/cowprotocol/docs/pull/344