Remove webrender from the README.

Author: nnethercote

collector/benchmarks/README.md

@@ -45,7 +45,6 @@ They mostly consist of real-world crates.
 - **unicode-normalization-0.1.19**: Unicode character composition and decomposition
   utilities. Uses huge `match` statements that stress the compiler in unusual
   ways.
-- **webrender**: A web renderer. Used by Firefox and Servo.
 - **webrender-2022**: A web renderer. A large, complex crate used by Firefox
   and Servo. Webrender isn't released regularly so this is a development
   version (revision da1df33). The `-2022` suffix distinguishes it from earlier