Reasoning: till now we're only compiling it when the changes land at the
`main` branch, which allows invalid changes to the mdbook to pass the PR
check. With the update at this commit we ensure that the new PRs pass
the mdbook compilation check.
Extend merkletree spec, init SignedPod section, add typos checker in CI
- extend merkletree spec, converting old hand-drawn diagrams to drawio
diagrams, and adding new diagrams (related: #6)
- init SignedPod section (related: #2)
- initial draft of the types dictionary, set, array (related: #26)
- add typos checker in CI (and correct the ones that were detected)
Note on drawio diagrams: each image file contains the metadata to edit the diagram in the draw.io website.
