docs: add benchmarking to torrent repo README

packages/torrent-repository/README.md

@@ -1,6 +1,27 @@
-# Torrust Tracker Configuration
+# Torrust Tracker Torrent Repository
 
-A library to provide torrent repository to the [Torrust Tracker](https://github.com/torrust/torrust-tracker).
+A library to provide a torrent repository to the [Torrust Tracker](https://github.com/torrust/torrust-tracker).
+
+## Benchmarking
+
+```console
+cargo bench -p torrust-tracker-torrent-repository
+```
+
+Example partial output:
+
+```output
+     Running benches/repository_benchmark.rs (target/release/deps/repository_benchmark-a9b0013c8d09c3c3)
+add_one_torrent/RwLockStd
+                        time:   [63.057 ns 63.242 ns 63.506 ns]
+Found 12 outliers among 100 measurements (12.00%)
+  2 (2.00%) low severe
+  2 (2.00%) low mild
+  2 (2.00%) high mild
+  6 (6.00%) high severe
+add_one_torrent/RwLockStdMutexStd
+                        time:   [62.505 ns 63.077 ns 63.817 ns]
+```
 
 ## Documentation