Needs better instructions

[Fjox]

trying to get this to work was confusing.

1. i didnt know there was a python packages, and i only found out because i looked in the issues tab
2. s3_media_upload is not properly documented, no mention what goes into database.yaml
3. i dont even know if this plugin does what i think it does due to very minimal description and after installation nothing was wrotten to the bucket
4. i have no clue what policies i would need to set in s3 or minio
5. how does endpoint url act (does it need http:// infront of it or not and are : supported at the end)

[Fjox]

3. synapse-s3-storage-provider only handles local files

[Fjox]

5. Cant connect when : is in the url