Fix typo

CONTRIBUTING.md

@@ -79,7 +79,7 @@ MIRI_TEST_TARGET=i686-unknown-linux-gnu ./miri test
 
 `./miri test FILTER` only runs those tests that contain `FILTER` in their filename (including the
 base directory, e.g. `./miri test fail` will run all compile-fail tests). These filters are passed
-to `cargo test`, so for multiple filers you need to use `./miri test -- FILTER1 FILTER2`.
+to `cargo test`, so for multiple filters you need to use `./miri test -- FILTER1 FILTER2`.
 
 #### Fine grained logging