More doc fixes

Author: Manishearth

clippy_lints/src/unwrap.rs

@@ -6,7 +6,7 @@ use rustc::hir::*;
 use syntax::ast::NodeId;
 use syntax::codemap::Span;
 
-/// **What it does:** Checks for calls of unwrap[_err]() that cannot fail.
+/// **What it does:** Checks for calls of `unwrap[_err]()` that cannot fail.
 ///
 /// **Why is this bad?** Using `if let` or `match` is more idiomatic.
 ///