Update Documentation installation and fix new beanie install method (#982)

* Update installation types and fix beanie install

* Move install instructions to redis authentication

* Add Redis install instructions

docs/configuration/authentication/strategies/redis.md

@@ -2,6 +2,14 @@
 
 [Redis](https://redis.io/) is an ultra-fast key-store database. As such, it's a good candidate for token management. In this strategy, a token is generated and associated with the user id. in the database. On each request, we try to retrieve this token from Redis to get the corresponding user id.
 
+## Installation
+
+You should install the library with the optional dependencies for Redis:
+
+```sh
+pip install 'fastapi-users[redis]'
+```
+
 ## Configuration
 
 ```py

docs/installation.md

@@ -8,12 +8,22 @@ You can add **FastAPI Users** to your FastAPI project in a few easy steps. First
 pip install 'fastapi-users[sqlalchemy]'
 ```
 
+
 ## With Beanie support
 
 ```sh
-pip install 'fastapi-users[mongodb]'
+pip install 'fastapi-users[beanie]'
 ```
 
+## With Redis authentication backend support
+
+Information on installing with proper database support can be found in the [Redis](configuration/authentication/strategies/redis.md) section.
+
+## With OAuth2 support
+
+Information on installing with proper database support can be found in the [OAuth2](configuration/oauth.md) section.
+
+
 ---
 
 That's it! In the next section, we'll have an [overview](./configuration/overview.md) of how things work.