Fix doc typo

Author: michaelwheeler

src/lib.rs

@@ -25,7 +25,7 @@ which can be used together with rust-encoding or encoding-rs.
 * Take (at least) a `input: &mut cssparser::Parser` parameter
 * Return `Result<_, ()>`
 * When returning `Ok(_)`,
-  the function must have consume exactly the amount of input that represents the parsed value.
+  the function must have consumed exactly the amount of input that represents the parsed value.
 * When returning `Err(())`, any amount of input may have been consumed.
 
 As a consequence, when calling another parsing function, either: