Updates for next Microkit release

[Ivan-Velickovic]

The next Microkit release will contain a breaking change regarding to channels and so we need to update both the tutorial guide and code.

Need to consider any other changes with the release that affect the tutorial as usual.

Other changes:

• [ ] page size description has changed.

[Willmish]

to track:

• [ ] will need to update part 1 description of protection_domain element and the later channel description as PPC parameter pp changed locations: https://github.com/au-ts/microkit_tutorial/blob/main/website/src/part1.md?plain=1#L81