cli: sync docs with docker/cli v29.2.0

Author: github-actions[bot]

data/engine-cli/docker.yaml

@@ -29,8 +29,7 @@ long: |-
 
     ### Environment variables
 
-    The following list of environment variables are supported by the `docker` command
-    line:
+    The following environment variables control the behavior of the `docker` command-line client:
 
     | Variable                      | Description                                                                                                                                                                                                                                                       |
     | :---------------------------- |:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|