Update README.md

Fix typo

Author: Munksgaard

README.md

@@ -20,7 +20,7 @@ compiletest_rs = "*"
 By default, `compiletest-rs` should be able to run on both stable, beta and
 nightly channels of rust. We use the [`tester`](tester) fork of Rust's builtin
 `test` crate, so that we don't have require nightly. If you are running nightly
-and want to use Rust's `test` crate directly, you to have the rustc development
+and want to use Rust's `test` crate directly, you need to have the rustc development
 libraries install (which you can get by running `rustup component add rustc-dev
 --target nightly`). Once you have the rustc development libraries installed, you
 can use the `rustc` feature to make compiletest use them instead of the `tester`