add info how to run benchmarks in CI

scripts/benchmarks/README.md

@@ -15,6 +15,22 @@ This will download and build everything in `~/benchmarks_workdir/` using the com
 
 The scripts will try to reuse the files stored in `~/benchmarks_workdir/`, but the benchmarks will be rebuilt every time. To avoid that, use `-no-rebuild` option.
 
+## Running in CI
+
+The benchmarks scripts are used in a GitHub Actions worflow, and can be automatically executed on a preconfigured system against any Pull Request.
+
+![compute benchmarks](workflow.png "Compute Benchmarks CI job")
+
+To execute the benchmarks in CI, navigate to the `Actions` tab and then go to the `Compute Benchmarks` action. Here, you will find a list of previous runs and a "Run workflow" button. Upon clicking the button, you will be prompted to fill in a form to customize your benchmark run. The only mandatory field is the `PR number`, which is the identifier for the Pull Request against which you want the benchmarks to run.
+
+You can also include additional benchmark parameters, such as environment variables or filters. For a complete list of options, refer to `$ ./main.py --help`.
+
+Once all the required information is entered, click the "Run workflow" button to initiate a new workflow run. This will execute the benchmarks and then post the results as a comment on the specified Pull Request.
+
+By default, all benchmark runs are compared against `baseline`, which is a well-established set of the latest data.
+
+You must be a member of the `oneapi-src` organization to access these features.
+
 ## Requirements
 
 ### Python