update readme

Author: blink1073

README.md

@@ -22,6 +22,10 @@ Each subdirectory is scoped to run only one AI/ML integration's suite of tests f
 Within each subdirectory you should expect to have:
 
 - `run.sh` -- A script that should handle any additional library installations and steps for executing the test suite. This script should not populate the Atlas database with any required test data.
+- `config.env` - A file that defines the following environment variables:
+  - `REPO_NAME` -- The name of the AI/ML framework repository that will get cloned
+  - `CLONE_URL` -- The Github URL to clone into the specified `DIR`
+  - `DATABASE` -- The optional database where the Atlas CLI will load your index configs
 - `database/` -- An optional directory used by `.evergreen/scaffold_atlas.py` to populate a MongoDB database with test data. Only provide this if your tests require pre-populated data.
 - `database/{collection}.json` -- An optional JSON file containing one or more MongoDB documents that will be uploaded to `$DATABASE.{collection}` in the local Atlas instance. Only provide this if your tests require pre-populated data.
 - `indexConfig.json` -- An optional file containing configuration for a specified Atlas Search Index.
@@ -40,12 +44,15 @@ The general layout of this repo looks like this:
 │   │   └── furthestSearch.json                 # Populates $DATABASE.furthestSearch
 │   ├── indexes                                 # Optional Index definitions directory
 │   │   └── indexConfig.json                    # Optional Search index definition
+|   ├── config.env                              # Configuration file
 │   └── run.sh                                  # Script that executes test
+|
 ├── semantic-kernel-python                      # Folder scoped for one Integration
 │   ├── database                                # Optional database definition
 │   │   └── nearestSearch.json                  # Populates $DATABASE.nearestSearch
 │   │   └── furthestSearch.json                 # Populates $DATABASE.furthestSearch
 │   ├── indexConfig.json                        # Creates Search Index on $DATABASE
+|   ├── config.env                              # Configuration file
 │   └── run.sh                                  # Script that executes test
 ```
 
@@ -97,9 +104,6 @@ Test execution flow is defined in `.evergreen/config.yml`. The test pipeline's c
 - [`expansions`](https://docs.devprod.prod.corp.mongodb.com/evergreen/Project-Configuration/Project-Configuration-Files/#expansions) -- Build variant specific variables. Expansions that need to be maintained as secrets should be stored in [the Evergreen project settings](https://spruce.mongodb.com/project/ai-ml-pipeline-testing/settings/variables) using [variables](https://docs.devprod.prod.corp.mongodb.com/evergreen/Project-Configuration/Project-and-Distro-Settings#variables). Some common expansions needed are:
 
   - `DIR` -- The subdirectory where the tasks will run
-  - `REPO_NAME` -- The name of the AI/ML framework repository that will get cloned
-  - `CLONE_URL` -- The Github URL to clone into the specified `DIR`
-  - `DATABASE` -- The optional database where the Atlas CLI will load your index configs
 
 - `run_on` -- Specified platform to run on. `rhel87-small` should be used by default. Any other distro may fail Atlas CLI setup.
 - `tasks` -- Tasks to run. See below for more details