[DOCS] Adds environment variable warning (#67623) (#68946)

* [DOCS] Adds wenvironment variable warning

* Updated note

docs/setup/docker.asciidoc

@@ -78,14 +78,16 @@ services:
 [[environment-variable-config]]
 ==== Environment variable configuration
 
-Under Docker, Kibana can be configured via environment variables. When
+Under Docker, {kib} can be configured via environment variables. When
 the container starts, a helper process checks the environment for variables that
 can be mapped to Kibana command-line arguments.
 
 For compatibility with container orchestration systems, these
 environment variables are written in all capitals, with underscores as
 word separators. The helper translates these names to valid
-Kibana setting names.
+{kib} setting names.
+
+WARNING: All information that you include in environment variables is visible through the `ps` command, including sensitive information.
 
 Some example translations are shown here: