Add transaction retry info to production checklist

v19.1/recommended-production-settings.md

@@ -513,3 +513,7 @@ When running CockroachDB on Kubernetes, making the following minimal customizati
 * Configure CPU and memory [resource requests and limits](kubernetes-performance.html#resource-requests-and-limits).
 
 For more information and additional customization suggestions, see our full detailed guide to [CockroachDB Performance on Kubernetes](kubernetes-performance.html).
+
+## Transaction Retries
+
+When several transactions are trying to modify the same underlying data concurrently, they may experience [contention](performance-best-practices-overview.html#understanding-and-avoiding-transaction-contention) that leads to [transaction retries](transactions.html#transaction-retries).  In order to avoid failures in production, your application should be engineered to handle transaction retries using [client-side retry handling](transactions.html#client-side-intervention).

v19.2/recommended-production-settings.md

@@ -514,3 +514,7 @@ When running CockroachDB on Kubernetes, making the following minimal customizati
 * Configure CPU and memory [resource requests and limits](kubernetes-performance.html#resource-requests-and-limits).
 
 For more information and additional customization suggestions, see our full detailed guide to [CockroachDB Performance on Kubernetes](kubernetes-performance.html).
+
+## Transaction Retries
+
+When several transactions are trying to modify the same underlying data concurrently, they may experience [contention](performance-best-practices-overview.html#understanding-and-avoiding-transaction-contention) that leads to [transaction retries](transactions.html#transaction-retries).  In order to avoid failures in production, your application should be engineered to handle transaction retries using [client-side retry handling](transactions.html#client-side-intervention).