Note that multiline variables are not supported

doc/ci/variables/README.md

@@ -262,6 +262,10 @@ variables](../../topics/autodevops/index.md#application-secret-variables) will
 then be available as environment variables on the running application
 container.
 
+CAUTION: **Caution:**
+Variables with multiline values are not currently supported, due to
+limitations with the current Auto DevOps scripting environment.
+
 ## Debug tracing
 
 > Introduced in GitLab Runner 1.7.

doc/topics/autodevops/index.md

@@ -730,6 +730,10 @@ metadata:
 type: Opaque
 ```
 
+CAUTION: **Caution:**
+Variables with multiline values are not currently supported, due to
+limitations with the current Auto DevOps scripting environment.
+
 NOTE: **Note:**
 Environment variables are generally considered immutable in a Kubernetes
 pod. Therefore, if you update an application secret without changing any