Rollup merge of #23329 - jbcrail:rm-syntax-highlight, r=sanxiyn

As suggested by @steveklabnik in #23254, I removed the redundant Rust syntax highlighting from the documentation.

src/librustc/middle/traits/project.rs

@@ -535,7 +535,7 @@ fn assemble_candidates_from_param_env<'cx,'tcx>(
 /// In the case of a nested projection like <<A as Foo>::FooT as Bar>::BarT, we may find
 /// that the definition of `Foo` has some clues:
 ///
-/// ```rust
+/// ```
 /// trait Foo {
 ///     type FooT : Bar<BarT=i32>
 /// }

src/librustc/middle/ty_walk.rs

@@ -82,7 +82,7 @@ impl<'tcx> TypeWalker<'tcx> {
     ///
     /// Example: Imagine you are walking `Foo<Bar<int>, uint>`.
     ///
-    /// ```rust
+    /// ```
     /// let mut iter: TypeWalker = ...;
     /// iter.next(); // yields Foo
     /// iter.next(); // yields Bar<int>