Contribution guidelines: Broken link

[Chealer]

The link to Spring Data contribution guidelines from Spring Data Commons' contribution guidelines file unfortunately yields a 404 error.
Instead of pointing to:
https://github.com/spring-projects/spring-data-build/blob/CONTRIBUTING.adoc
...the file should link to:
https://github.com/spring-projects/spring-data-build/blob/main/CONTRIBUTING.adoc

[mp911de]

Good catch, that's fixed now.