add env vars documentation to readme

Author: garysassano

collector/README.md

@@ -163,6 +163,15 @@ from an S3 object using a CloudFormation template:
 
 Loading configuration from S3 will require that the IAM role attached to your function includes read access to the relevant bucket.
 
+## Environment Variables
+
+The following environment variables can be used to configure the OpenTelemetry collector Lambda extension:
+
+| Variable Name                        | Value                                                                          | Description                                                                                                                                                                                                                                                 |
+| ------------------------------------ | ------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `OPENTELEMETRY_COLLECTOR_CONFIG_URI` | URI (e.g., `/var/task/collector.yaml`, `http://...`, `s3://...`)               | Specifies the location of the OpenTelemetry Collector configuration file. This can be a path within the function's deployment package, an HTTP URI, or an S3 URI. If loading from S3, the function's IAM role needs read access to the specified S3 object. |
+| `OPENTELEMETRY_EXTENSION_LOG_LEVEL`  | `debug`, `info`, `warn`, `error`, `dpanic`, `panic`, `fatal` (Default: `info`) | Controls the logging level of the OpenTelemetry Lambda extension itself.                                                                                                                                                                                    |
+
 ## Auto-Configuration
 
 Configuring the Lambda Collector without the decouple processor and batch processor can lead to performance issues. So the OpenTelemetry Lambda Layer automatically adds the decouple processor to the end of the chain if the batch processor is used and the decouple processor is not.

pr_template.md

@@ -0,0 +1,22 @@
+<!-- Provide a general summary of your changes in the Title above -->
+
+## Description
+This PR adds documentation for the environment variables used to configure the OpenTelemetry Lambda Collector extension.
+
+## Changes
+* Added an "Environment Variables" section to `collector/README.md`.
+* Documented `OPENTELEMETRY_COLLECTOR_CONFIG_URI` and `OPENTELEMETRY_EXTENSION_LOG_LEVEL` in a table format, including their descriptions and possible values.
+
+## Testing
+N/A - Documentation change only.
+
+## Related Issues
+<!-- List any related issues this PR resolves (e.g., "Resolves #123") -->
+
+## Checklist:
+<!-- Go over all the following points, and put an `x` in all the boxes that apply. -->
+<!-- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+- [x] My code follows the code style of this project.
+- [x] I have updated the documentation accordingly.
+- [ ] I have added tests to cover my changes. (Not applicable)
+- [x] All new and existing tests passed. (Not applicable)