Add doc comments to config

src/main.rs

@@ -12,10 +12,15 @@ use crate::ingestion::routes::{monzo_batched_csv, monzo_batched_json, monzo_upda
 
 #[derive(Debug, clap::Parser)]
 struct Config {
+    /// If we should perform migration on startup.
     #[clap(short, long, env, default_value_t = true)]
     migrate: bool,
+
+    /// The server address to bind to.
     #[clap(short, long, env, default_value = "0.0.0.0:3000")]
     addr: SocketAddr,
+
+    /// URL to PostgreSQL database.
     #[clap(short, long = "db", env)]
     database_url: String,
 }