Fix trailing whitespace

Author: atlasgorn

src/doc/rustc/src/profile-guided-optimization.md

@@ -151,7 +151,7 @@ to use PGO with Rust.
 As an alternative to directly using the compiler for Profile-Guided Optimization,
 you may choose to go with `cargo-pgo`, which has an intuitive command-line API
 and saves you the trouble of doing all the manual work. You can read more about
-it in their repository accessible from this link: [Kobzol/cargo-pgo](https://github.com/Kobzol/cargo-pgo) 
+it in their repository accessible from this link: [Kobzol/cargo-pgo](https://github.com/Kobzol/cargo-pgo)
 
 For the sake of completeness, here are the corresponding steps using `cargo-pgo`: