add pytest-benchmark to benchmarking section (#596)

Adds
[pytest-benchmark](https://pytest-benchmark.readthedocs.io/en/stable/)
as another benchmarking option.

@ruaridhg and I used this recently on the HEFTIE project to benchmark
reading / writing ome-zarr images. It was a useful alternative to `asv`,
as we didn't need to track performance over time (rather just benchmark
specific functions / packages).

Potentially @connoraird used this on a project recently too (?) - if so,
do double check that you agree with my points here. If you ended up
going for another benchmarking package, maybe we can add that in too
:smile:

---------

Co-authored-by: Sam Cunliffe <samcunliffe@users.noreply.github.com>

Author: K-Meech

docs/pages/benchmarking-profiling.md

@@ -5,9 +5,10 @@ layout: default
 
 ## Benchmarking
 
-| Name                                         | Short description                                                                                                                                                                                                                                                                                                                                                                         |                     🚦                      |
-| -------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-----------------------------------------: |
-| [asv](https://asv.readthedocs.io/en/stable/) | A tool for benchmarking Python packages over their lifetime. Allows you to write benchmarks and then run them against every commit in the repository, to identify where performance increased or decreased. Comparative benchmarks can also be run, which can be useful for [running them in CI using GitHub runners](https://labs.quansight.org/blog/2021/08/github-actions-benchmarks). | <span class="label label-green">Best</span> |
+| Name                                                                  | Short description                                                                                                                                                                                                                                                                                                                                                                         |                      🚦                      |
+| --------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :------------------------------------------: |
+| [asv](https://asv.readthedocs.io/en/stable/)                          | A tool for benchmarking Python packages over their lifetime. Allows you to write benchmarks and then run them against every commit in the repository, to identify where performance increased or decreased. Comparative benchmarks can also be run, which can be useful for [running them in CI using GitHub runners](https://labs.quansight.org/blog/2021/08/github-actions-benchmarks). | <span class="label label-green">Best</span>  |
+| [pytest-benchmark](https://pytest-benchmark.readthedocs.io/en/stable) | Provides a benchmark fixture with full pytest integration, and the ability to compare performance between multiple runs. A simple, light-weight alternative to asv that we've found to be useful.                                                                                                                                                                                         | <span class="label label-yellow">Good</span> |
 
 ## Profiling