Update compatibility matrix documentation

[mp911de]

The documentation doesn't list the 2021.1 release train yet: https://docs.spring.io/spring-data/mongodb/docs/current/reference/html/#compatibility.matrix

[christophstrobl]

2021.1 has already been added by #4052. But we're missing 2023.0 so I'll repurpose the ticket to update the matrix accordingly.