Add note on how to enable the optional dependency

diff --git a/README.md b/README.md
index 3159a3e8979c8219320cb904b932bf1e904ad7e9..db3eca865ebc3105aeb3bf51e9954ccf016ac961 100644 (file)
--- a/README.md
+++ b/README.md
@@ -286,6 +286,8 @@ And, in your `main.rs` or `lib.rs`:
 #![cfg_attr(feature="clippy", plugin(clippy))]
 ```
 
+Then build by enabling the feature: `cargo build --features "clippy"`
+
 Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
 `cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
 (the `-Z no trans`, while not neccessary, will stop the compilation process after