GH-4: Add code snippets

Author: ArtyomVancyan

README.md

@@ -1,19 +1,66 @@
 # fastapi-oauth2 <img src="https://github.com/pysnippet.png" align="right" height="64" />
 
-Easy to setup OAuth2 authentication with support for several auth providers.
+[//]: # (TODO: LONG DESCRIPTION)
+
+## Features to be implemented
+
+- Use multiple OAuth2 providers at the same time
+    * There need to be provided a way to configure the OAuth2 for multiple providers
+- Token -> user data, user data -> token easy conversion
+- Customize OAuth2 routes
 
 ## Installation
 
 ```shell
 python -m pip install fastapi-oauth2
 ```
 
-## Features to be implemented
+## Configuration
 
-- Use multiple OAuth2 providers at the same time
-    * There need to be provided a way to configure the OAuth2 for multiple providers
-- Token -> user data, user data -> token easy conversion
-- Customize OAuth2 routes
+[//]: # (TODO: LONG DESCRIPTION)
+
+```python
+from fastapi_oauth2.client import OAuth2Client
+from fastapi_oauth2.config import OAuth2Config
+from social_core.backends.github import GithubOAuth2
+
+oauth2_config = OAuth2Config(
+    allow_http=True,
+    jwt_secret=os.getenv("JWT_SECRET"),
+    jwt_expires=os.getenv("JWT_EXPIRES"),
+    jwt_algorithm=os.getenv("JWT_ALGORITHM"),
+    clients=[
+        OAuth2Client(
+            backend=GithubOAuth2,
+            client_id=os.getenv("OAUTH2_CLIENT_ID"),
+            client_secret=os.getenv("OAUTH2_CLIENT_SECRET"),
+            scope=["user:email"],
+        ),
+    ]
+)
+```
+
+## Usage
+
+[//]: # (TODO: LONG DESCRIPTION)
+
+```python
+from fastapi import FastAPI
+from fastapi_oauth2.middleware import OAuth2Middleware
+
+app = FastAPI()
+app.add_middleware(OAuth2Middleware, config=oauth2_config)
+```
+
+[//]: # (TODO: LONG DESCRIPTION)
+
+```jinja2
+{% if request.user.is_authenticated %}
+    <a href="/oauth2/logout">Sign out</a>
+{% else %}
+    <a href="/oauth2/github/auth">Sign in</a>
+{% endif %}
+```
 
 ## Contribute