Add Solr 8.8.0 back-compat issue notice on downloads page (#36)

* Add Solr 8.8.0 back-compat issue notice on downloads page.
diff --git a/content/pages/solr/downloads.md b/content/pages/solr/downloads.md
index 667e01b..4592408 100644
--- a/content/pages/solr/downloads.md
+++ b/content/pages/solr/downloads.md
@@ -6,3 +6,10 @@
 Official releases are usually created when the [developers]({filename}/pages/whoweare.md)
 feel there are sufficient changes, improvements and bug fixes to warrant a release.
 Due to the voluntary nature of Solr, no releases are scheduled in advance.
+
+#### Apache Solr 8.8.0 update
+Solr 8.8.0 has been reported to have back-compat issues with SolrJ. 
+
+Client applications that use a SolrJ version prior to 8.8.0 may experience a NullPointerException in ZkCoreNodeProps when requesting cluster state from Zookeeper. Upgrading your application to use SolrJ 8.8.0 will fix the issue.
+
+A release with the fix is currently being worked on.