chore: update readme for 0.1.3

README.md

@@ -10,16 +10,20 @@ cargo add parenv
 
 ## Usage
 
-The following demonstrates a simple usage example. `parenv` relies on the `FromStr` trait to parse environment variables into the specified type.
-The documentation comment on each field is used as the description for the corresponding environment variable.
-To make a field optional wrap the type with an `Option`.
+Here are some important features you should know about.
+
+- `parenv` relies on the `FromStr` trait to parse environment variables into the specified type.
+- The documentation comment on each field is used as the description for the corresponding environment variable.
+- To make a field optional, wrap the type with an `Option`.
+- To set a prefix value, set the attribute `#[parenv(prefix = "ENV_")]` on your struct.
 
 ```rust
 use std::{net::SocketAddr, path::PathBuf};
 
 use parenv::Environment;
 
 #[derive(Debug, Environment)]
+#[parenv(prefix = "ENV_")]
 struct Env {
     /// The cat
     cat: Option<u8>,