message: Added missing file extension
diff: @@ -134,7 +134,7 @@ let out_dir = env::var("OUT_DIR").unwrap();
  [configuration]: https://doc.rust-lang.org/reference/attributes.html#conditional-compilation
  [clang]: http://clang.llvm.org/docs/CrossCompilation.html#target-triple
  [jobserver]: https://www.gnu.org/software/make/manual/html_node/Job-Slots.html
  -[cargo-config]: reference/config
  +[cargo-config]: reference/config.html
  ### Environment variables Cargo sets for 3rd party subcommands
  