fix(docs): correct Redis conf field description

apps/emqx_connector/i18n/emqx_connector_redis.conf

@@ -69,7 +69,7 @@ The Redis default port 6379 is used if `[:Port]` is not specified.
 A Node list for Cluster to connect to. The nodes should be separated with commas, such as: `Node[,Node].`
 For each Node should be: The IPv4 or IPv6 address or the hostname to connect to.
 A host entry has the following form: `Host[:Port]`.
-The MongoDB default port 27017 is used if `[:Port]` is not specified.
+The Redis default port 6379 is used if `[:Port]` is not specified.
 """
           zh: """