Document issue with older fdb bindings and DNS support (FoundationDB#1956)

* Document issue with older fdb bindings and DNS support

Author: johscheuer

.gitignore

@@ -44,3 +44,6 @@ dist/
 
 # Ignore any temporary created kube config files
 *.kubeconfig
+
+# Used for testing locally build FDB library
+libfdb_c.so

docs/manual/operator_customization.md

@@ -19,7 +19,10 @@ At start time, the operator scans this directory for version-specific binaries,
 
 ## Customizing the Primary Client Library
 
-By default, the primary client library used by the operator is the oldest supported version, as discussed above. If you want to use a newer version of the client library as your primary client, you can control that through additonal init containers. 
+By default, the primary client library used by the operator is the oldest supported version, as discussed above.
+If you want to use a newer version of the client library as your primary client, you can control that through additional init containers.
+**NOTE**: When using this approach it can happen that the operator keeps crashing when all coordinators are deleted, see https://github.com/apple/foundationdb/issues/11222.
+A better solution is to build the operator with the `7.1` version to prevent those crashes.
 
 ```yaml
 # This provides partial configuration for the deployment to show what needs to change in order to
@@ -72,4 +75,4 @@ apiVersion: apps/v1
 
 ## Next
 
-You can continue on to the [next section](replacements_and_deletions.md) or go back to the [table of contents](index.md).
+You can continue on to the [next section](replacements_and_deletions.md) or go back to the [table of contents](index.md).