Linked benchmarks do not benchmark this crate

[tryoxiss]

In the README, you say this crate "does very well in benchmarks", linking json-benchmark. That repository benchmarks 3 JSON libraries for rust, none of which are this one.

The three benchmarked are (taken directly from thier README, but I added the deprecated warning)

• serde_json 1.0.72
• (DEPRECTAED) rustc-serialize 0.3.24
• simd-json 0.4.11 (this requires a modern x86 CPU for good results)

Maybe they benchmarked this at some point in the past (though it seems unlikely they would remove a crate from benchmarks), but they certinly don't now.