Fix dead link to benchmarks.ipynb (#14842)

Notebook has been updated here https://github.com/huggingface/notebooks/tree/master/examples/benchmark.ipynb

docs/source/benchmarks.mdx

@@ -16,7 +16,7 @@ specific language governing permissions and limitations under the License.
 
 Let's take a look at how 🤗 Transformer models can be benchmarked, best practices, and already available benchmarks.
 
-A notebook explaining in more detail how to benchmark 🤗 Transformer models can be found [here](https://github.com/huggingface/transformers/tree/master/notebooks/05-benchmark.ipynb).
+A notebook explaining in more detail how to benchmark 🤗 Transformer models can be found [here](https://github.com/huggingface/notebooks/tree/master/examples/benchmark.ipynb).
 
 ## How to benchmark 🤗 Transformer models