Use log crate for logging instead of println

README.md

@@ -11,4 +11,5 @@ They should be defined where the binary is located or above it in an `.env` file
 - `THUMBNAILS` is a path where generated thumbnails should be stored
 - `BIND_URL` is the url and port to bind to (typically your own IP address)
 - `SECRET_KEY` is the *hopefully* random string to sign Tokens with
+- `RUST_LOG` is one of `off, error, warn, info, debug, trace`, from least to most noisy [error is default]