Merge pull request #14555 from terraform-providers/f-custom-user-agen…

…t-info

provider/config: configure additional user-agent information with env var

website/docs/index.html.markdown

@@ -104,6 +104,14 @@ If you're running Terraform on CodeBuild or ECS and have configured an [IAM Task
 
 If you're running Terraform on EKS and have configured [IAM Roles for Service Accounts (IRSA)](https://docs.aws.amazon.com/eks/latest/userguide/iam-roles-for-service-accounts.html), Terraform will use the pod's role. This support is based on the underlying `AWS_ROLE_ARN` and `AWS_WEB_IDENTITY_TOKEN_FILE` environment variables being automatically set by Kubernetes or manually for advanced usage.
 
+### Custom User-Agent Information
+
+By default, the underlying AWS client used by the Terraform AWS Provider creates requests with User-Agent headers including information about Terraform and AWS Go SDK versions. To provide additional information in the User-Agent headers, the `TF_APPEND_USER_AGENT` environment variable can be set and its value will be directly added to HTTP requests. e.g.
+
+```sh
+$ export TF_APPEND_USER_AGENT="JenkinsAgent/i-12345678 BuildID/1234 (Optional Extra Information)"
+```
+
 ### EC2 Instance Metadata Service
 
 If you're running Terraform from an EC2 instance with IAM Instance Profile