Stop linking to a patch-specific version of rabbitmqadmin

Linking to a stable release series branch name should be enough.
This would somewhat simplify doc imports for the VMware RabbitMQ
documentation pipeline.

Author: michaelklishin

site/management-cli.md

@@ -35,9 +35,7 @@ HTTP API intentionally doesn't expose certain operations.
 the management plugin enabled. Navigate to `http://{hostname}:15672/cli/rabbitmqadmin` to download it.
 The tool requires a supported version of Python to be installed.
 
-Alternatively, the version of `rabbitmqadmin` which
-corresponds with the management plugin version &version-server;
-can be downloaded [from GitHub](https://raw.githubusercontent.com/rabbitmq/rabbitmq-server/&version-server-tag;/deps/rabbitmq_management/bin/rabbitmqadmin).
+Alternatively, `rabbitmqadmin` can be downloaded [from GitHub](https://raw.githubusercontent.com/rabbitmq/rabbitmq-server/v3.11.x/deps/rabbitmq_management/bin/rabbitmqadmin).
 
 
 ## Getting Started