Improve error message when exchange manager is not configured

Once the documentation is available we may also want to extend the
message with a reference to failure recovery documentation.

core/trino-main/src/main/java/io/trino/exchange/ExchangeManagerRegistry.java

@@ -102,7 +102,7 @@ public ExchangeManager getExchangeManager()
     {
         ExchangeManager exchangeManager = this.exchangeManager;
         if (exchangeManager == null) {
-            throw new TrinoException(EXCHANGE_MANAGER_NOT_CONFIGURED, "Exchange manager is not configured");
+            throw new TrinoException(EXCHANGE_MANAGER_NOT_CONFIGURED, "Exchange manager must be configured for the failure recovery capabilities to be fully functional");
         }
         return exchangeManager;
     }