docs: usage - configuration

README.md

@@ -41,15 +41,56 @@ Alongside an abstract database access layer, repositories also support:
    yarn add @flex-development/dreepo # or npm i @flex-development/dreepo
    ```
 
-## :construction: Usage
+## Usage
+
+[Configuration](#configuration)  
+[Creating a New Model & Repository](#creating-a-new-model-&-repository)  
+[CRUD Operations](#crud-operations)  
+[Schema Validation](#schema-validation)  
+[Contributing](docs/CONTRIBUTING.md)
+
+### Configuration
+
+#### Firebase Service Account
+
+1. Navigate to [Service Accounts][7] section of the Firebase console
+
+2. Click **Generate New Private Key** to generate a new service account key file
+   if you do not have one already
+
+   Dreepo communicates with your Realtime Database using the [Firebase Database
+   REST API][2].
+
+   [Google OAuth2 access tokens][8], generated by service accounts, are used to
+   authenticate requests.
+
+#### Environment Variables
+
+- `DEBUG`: Toggle [debug][9] logs from the `dreepo` namespace
+- `DEBUG_COLORS`: Toggle [debug][9] log namespace colors
+- `FIREBASE_CLIENT_EMAIL`: Firebase Admin service account `client_email`
+- `FIREBASE_DATABASE_URL`: Firebase Realtime Database URL
+- `FIREBASE_PRIVATE_KEY`: Firebase Admin service account `private_key`
+
+### Creating a New Model & Repository
+
+**TODO**: Update documentation.
+
+### CRUD Operations
+
+**TODO**: Update documentation.
+
+### Schema Validation
 
 **TODO**: Update documentation.
 
 ## Built With
 
-- [Axios][7] - Promise based HTTP client
+- [Axios][10] - Promise based HTTP client
 - [Firebase Database REST API][2] - REST API for Firebase Realtime Database
-- [Google APIs Node.js Client][8] - Node.js client library for using Google APIs
+- [Google APIs Node.js Client][11] - Node.js client library for using Google
+  APIs
+- [debug][9] - JavaScript debugging utility
 - [mingo][3] - MongoDB query language for in-memory objects
 - [runtypes][4] - Runtime validation for static types
 
@@ -61,5 +102,9 @@ Alongside an abstract database access layer, repositories also support:
   https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token
 [6]:
   https://docs.github.com/en/developers/apps/scopes-for-oauth-apps#available-scopes
-[7]: https://github.com/axios/axios
-[8]: https://github.com/googleapis/google-api-nodejs-client
+[7]:
+  https://console.firebase.google.com/project/_/settings/serviceaccounts/adminsdk
+[8]: https://developers.google.com/identity/protocols/oauth2
+[9]: https://github.com/visionmedia/debug
+[10]: https://github.com/axios/axios
+[11]: https://github.com/googleapis/google-api-nodejs-client