Add documentation about scylla's aio-max-nr in the crate's root docs

src/main.rs

@@ -23,6 +23,22 @@
 //! To stop the database cluster at any time, run `docker compose down`. To stop it and delete the
 //! volumes (resetting the database), run `docker compose down -v`.
 //! 
+//! Before booting up scylla, you'll need to set the `aio-max-nr` kernel parameter to `1048576` or
+//! higher. You can check [Scylla's documentation](https://hub.docker.com/r/scylladb/scylla) for
+//! the math of the value at which you'll need to set the parameter. In linux, you can set it by
+//! running:
+//! 
+//! ```shell
+//! $ sudo sysctl -w fs.aio-max-nr=1048576
+//! ```
+//! 
+//! That will set it up for your current session. To make it persistent across reboots, add the
+//! following to your `/etc/sysctl.conf` file (or to a new file in `/etc/sysctl.d/`):
+//! 
+//! ```conf
+//! fs.aio-max-nr = 1048576
+//! ```
+//!
 //! ## Booting Up
 //!
 //! Payphone has a CLI interface that allows you to pass the bot token and database URL as CLI