Fix warning on rustdoc

Rustdoc was treating doc comments containing `#[non_exhaustive]`
as links and warning, so mark that as code to avoid the warning.

Author: jmerdich

src/codegen/mod.rs

@@ -2279,7 +2279,7 @@ impl MethodCodegen for Method {
 pub enum EnumVariation {
     /// The code for this enum will use a Rust enum
     Rust {
-        /// Indicates whether the generated struct should be #[non_exhaustive]
+        /// Indicates whether the generated struct should be `#[non_exhaustive]`
         non_exhaustive: bool,
     },
     /// The code for this enum will use a newtype

src/lib.rs

@@ -909,7 +909,7 @@ impl Builder {
     }
 
     /// Mark the given enum (or set of enums, if using a pattern) as a Rust
-    /// enum with the #[non_exhaustive] attribute.
+    /// enum with the `#[non_exhaustive]` attribute.
     ///
     /// This makes bindgen generate enums instead of constants. Regular
     /// expressions are supported.