Update links to Github repos and use tags

[miltonjonat]

The links to Github repos throughout the docs are not using tags, and some are outdated. I believe we should always use tags to ensure the links remain valid after new releases.

Example:

• At the end of the "Assets handling" page, there is a link to the rollups repository where one can find a list of the Portals and their corresponding encodings. This is pointing to https://github.com/cartesi/rollups#portals, but that is no longer the location of that information (it is now in https://github.com/cartesi/rollups-contracts/tree/v1.1.0#portals). If tags had been used it would still be working (e.g., https://github.com/cartesi/rollups/tree/v1.0.0#portals)

I expect there to be a lot of references to Github repos without tags around the docs, so a thorough search and replace would be welcome.

[ATREAY]

Hey @miltonjonat, can I work on this issue if you are not already working on it?

[masiedu4]

Hey, @ATREAY I think the link has been fixed but if there are any additions/outstanding ones, kindly make a fix and add me as a reviewer