Update README.md

Author: samber

README.md

@@ -32,6 +32,7 @@ A Syslog Handler for [slog](https://pkg.go.dev/log/slog) Go library.
 - [slog-multi](https://github.com/samber/slog-multi): `slog.Handler` chaining, fanout, routing, failover, load balancing...
 - [slog-formatter](https://github.com/samber/slog-formatter): `slog` attribute formatting
 - [slog-sampling](https://github.com/samber/slog-sampling): `slog` sampling policy
+- [slog-mock](https://github.com/samber/slog-mock): `slog.Handler` for test purposes
 
 **HTTP middlewares:**