Fix type in readme

Author: wesleywiser

README.md

@@ -3,6 +3,6 @@ Support crate for rustc's self-profiling feature
 
 This crate is maintained by the Rust compiler team and in particular by the
 [self-profile working group][wg-self-profile]. It is currently only meant to
-be used within rustc itself, so APIs my change at any moment.
+be used within rustc itself, so APIs may change at any moment.
 
 [wg-self-profile]: https://github.com/rust-lang/compiler-team/blob/master/working-groups/self-profile/README.md