Document DEFAULT_MAX_WORKERS

Signed-off-by: Mazz Mosley <[email protected]>

docs/cli.md

@@ -193,6 +193,12 @@ the daemon.
 
 Configures the path to the `ca.pem`, `cert.pem`, and `key.pem` files used for TLS verification. Defaults to `~/.docker`.
 
+### DEFAULT\_MAX\_WORKERS
+
+Configures the maximum number of worker threads to be used when executing
+commands in parallel. Only a subset of commands execute in parallel, `stop`,
+`kill` and `rm`.
+
 ## Compose documentation
 
 - [User guide](/)