Fix broken link in README.md (#49)

Thanks a lot, good catch!

Author: zstadler

README.md

@@ -80,7 +80,7 @@ The original idea of this project is to avoid using tile servers altogether. Ins
 
 This replaces a running service with a pure, file-system-level implementation. Since the Linux kernel's file caching is among the highest-performing and most thoroughly tested codes ever written, it delivers serious performance.
 
-I run some [benchmarks](docs/quick_notes/http_benchmark.md) on a Hetzner server, the aim was to saturate a gigabit connection. At the end, it was able to serve 30 Gbit on loopback interface, on cold nginx cache.
+I run some [benchmarks](docs/benchmark/README.md) on a Hetzner server, the aim was to saturate a gigabit connection. At the end, it was able to serve 30 Gbit on loopback interface, on cold nginx cache.
 
 ## Code structure