docs: Update README.md

README.md

@@ -1,3 +1,57 @@
 # Freedom Config
 
-Create a Freedom configuration
+Utilities for creating an ATLAS Freedom configuration
+
+## Usage
+
+The `freedom-config` API provides an easy to use builder type for constructing
+the configuration, which can be invoked with the following:
+
+```rust
+use freedom_config::{Config, Test};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+	let config = Config::builder()
+	    .environment(Test)
+		.key("my_key")
+		.secret("my_secret")
+		.build()?;
+
+	println!("{:?}", config);
+
+	Ok(())
+}
+```
+
+The builder can also be used to source these items from the environment:
+
+```rust
+use freedom_config::Config;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+	std::env::set_var(Config::ATLAS_ENV_VAR, "Test");
+	std::env::set_var(Config::ATLAS_KEY_VAR, "my_key");
+	std::env::set_var(Config::ATLAS_SECRET_VAR, "my_secret");
+
+	let config = Config::builder()
+	    .environment_from_env()?
+		.key_from_env()?
+		.secret_from_env()?
+		.build()?;
+
+	println!("{:?}", config);
+
+	Ok(())
+}
+```
+
+Since this is fairly common, there is also a shorthand for constructing the
+config entirely from environment variables
+
+```rust
+use freedom_config::Config;
+
+fn main() {
+	let config = Config::from_env();
+}
+```