Add support for S3-backed image storage

README.md

@@ -76,6 +76,15 @@ __Other Variables__
 * `THEME_COLOR` - default `8fb677`. Specifies the hex value of the color to use on info message
   embeds
 
+Images can be uploaded directly when all of these settings are supplied:
+
+ * `S3_BUCKET` - bucket
+ * `S3_REGION` - bucket region
+ * `S3_ACCESS_KEY_ID` and `S3_SECRET_ACCESS_KEY` - credentials
+ * `S3_PUBLIC_URL` - public base URL. Objects must be publicly readable through this URL.
+ * `NSFW_CHECK_ENABLED` - enables the use of a small model to block uploading
+   of NSFW images. Set it to `false` to skip NSFW moderation and model initialization.
+
 ## Running with Docker
 
 A `compose.yml` file is provided to aid in running the bot agnostically using docker.