DRIVERS-1483 Add error label to retryable writes PoolClearedError prose test (#1024)

Author: patrickfreed

source/retryable-reads/tests/README.rst

@@ -182,7 +182,8 @@ PoolClearedError Retryability Test
 ==================================
 
 This test will be used to ensure drivers properly retry after encountering PoolClearedErrors.
-This test MUST be implemented by any driver that implements the CMAP specification.
+It MUST be implemented by any driver that implements the CMAP specification.
+This test requires MongoDB 4.2.9+ for ``blockConnection`` support in the failpoint.
 
 1. Create a client with maxPoolSize=1 and retryReads=true. If testing against a
    sharded deployment, be sure to connect to only a single mongos.

source/retryable-writes/tests/README.rst

@@ -330,7 +330,7 @@ and sharded clusters.
 
 #. Test that drivers properly retry after encountering PoolClearedErrors. This
    test MUST be implemented by any driver that implements the CMAP
-   specification.
+   specification. This test requires MongoDB 4.2.9+ for ``blockConnection`` support in the failpoint.
 
    1. Create a client with maxPoolSize=1 and retryWrites=true. If testing
       against a sharded deployment, be sure to connect to only a single mongos.
@@ -344,7 +344,8 @@ and sharded clusters.
                failCommands: ["insert"],
                errorCode: 91,
                blockConnection: true,
-               blockTimeMS: 1000
+               blockTimeMS: 1000,
+               errorLabels: ["RetryableWriteError"]
            }
        }