Repeating Backup Solr Version is confusing (#476)

Previous version implied solr had to be less than 8.9.0, but incremental backup is introduced in 8.9.0. Instead of “or older” vs “or newer” >= 8.9.0 is used, as this is more clear for non native English speakers and matches other version info in the document.
diff --git a/docs/solr-backup/README.md b/docs/solr-backup/README.md
index e771947..aa1c944 100644
--- a/docs/solr-backup/README.md
+++ b/docs/solr-backup/README.md
@@ -109,7 +109,7 @@
 _Since v0.5.0_
 
 The Solr Operator enables taking recurring updates, at a set interval.
-Note that this feature requires a SolrCloud running Solr `8.9.0` or older, because it relies on `Incremental` backups.
+Note that this feature requires a SolrCloud running Solr >= `8.9.0`, because it relies on `Incremental` backups.
 
 By default the Solr Operator will save a maximum of **5** backups at a time, however users can override this using `SolrBackup.spec.recurrence.maxSaved`.
 When using `recurrence`, users must provide a Cron-style `schedule` for the interval at which backups should be taken.