docs: Updating docs with docgen-solidity

[RafaDSan]

closes #228

Updating the current docs files with the command npx hardhat docgen so that the md files are up to date with the latest smart contracts

Uploading the first version of the md files generated by solidity-docgen It's important to note that they are not edited or reviewed yet, and they will be in the gitbook.

Gitbook account created
Gitbook invitation sent to @0xneves, @heronlancellot, @RafaDSan, @danimim to have edit access inside the Blockful project.

md files generated with solidity-docgen

• Next steps: After the merge of this PR, the gitbok will be updated and therefore I'll be able to refine it with the help of Camilia and @danimim!

[0xneves]

Approving these changes, thank you @RafaDSan