Update Pitest and Descartes versions in the examples

[ismail2ov]

Since we already have version 1.3.3, I have taken the liberty of updating Pitest and Descartes versions in README.md and how-to.md examples

I also added links to two sample repositories that demonstrate effective mutation testing in Spring Boot 3 — one using Maven and the other using Gradle.

@oscarlvp if you see that they are not suitable, tell me and revert the commit

[oscarlvp]

@ismail2ov thank you for your contribution, however, when #150 will be merged, the documentation and examples will be in a different place and version should be updated automatically with a new release.
Actually it should have been the case, but maybe the update was interrupted at some point.
In any case I would prefer to merge #150 first.

[oscarlvp]

New website has the examples and version should be updated on deploy.