message: Fix typo on README.md markdown
diff: @@ -38,7 +38,7 @@ TODO: Above link may be incorrect, protocol now called TLS instead of SSL?
  As documented in the [env_logger documentation](https://docs.rs/env_logger/),
  the `RUST_LOG` environment variable can be used to selectively enable log messages
  from Rust code. This works for Neqo's cmdline tools, as well as for when Neqo is
  -incorporated into Gecko, although [Gecko needs to be built in debug mode]((https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Configuring_Build_Options).
  +incorporated into Gecko, although [Gecko needs to be built in debug mode](https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Configuring_Build_Options).
  Some examples:
  1. `RUST_LOG=neqo_transport::dump ./mach run` lists sent and received QUIC
  