`The generate function` section of `Factories` chapter needs a fix

[Alexander Uvizhev]

I believe the generate function in the Factories is actually a init_view function so the section needs a fix.
https://aaronerhardt.github.io/relm4-book/book/factory.html#the-generate-function

[Alexander Uvizhev]

Also update function, and it seems both chapters about Factories aren't in sync with 0.4 API.

[Aaron Erhardt]

Thanks for pointing this out. The reason for this is that just after the release of 0.4 the work on the next release started unexpectedly quick, so I haven't had time to update the book and many parts need to be updated anyway once 0.5 is released.

However, I added a migration guide that explains all breaking changes: https://relm4.org/book/0_2_to_0_4.html

Btw. this is the "legacy" repository, the book is now developed here