OSSRH does no longer exist but still is referenced in flattenMode #497
Description
The flattenMode with value ossrh refers to the no longer existing OSSRH offering from Sonatype. This was replaced by Central Portal (https://central.sonatype.org/news/20250326_ossrh_sunset/). The documentation for https://www.mojohaus.org/flatten-maven-plugin/flatten-mojo.html#flattenMode needs to be updated as well as the link is no longer existing. Probably deprecating ossrh as value and introduce a new value centralportal would make sense.