Clarify documentation on running Earl reports

Author: mielvds

CONTRIBUTING.rst

@@ -7,9 +7,10 @@ Code
 ----
 
 * In general, follow the common `PEP 8 Style Guide`_.
-* Try to make the code pass flake8_ checks.
-
-  * ``flake8 lib/pyld/jsonld.py``
+* Try to make the code pass ruff_ checks.
+  * ``make lint`` or ``ruff check lib/pyld/*``
+  * you can also apply automatic fixing and formatting 
+    using ``make fmt``
 
 * Use version X.Y.Z-dev in dev mode.
 * Use version X.Y.Z for releases.
@@ -55,10 +56,7 @@ As of early 2020, the process to generate an EARL report for the official
 `JSON-LD Processor Conformance`_ page is:
 
 * Run the tests on the ``json-ld-api`` and ``json-ld-framing`` test repos to
-  generate a ``.jsonld`` test report:
-
-  * ``python tests/runtests.py ../json-ld-api/tests/ ../json-ld-framing/tests/ -e pyld-earl.jsonld``
-
+  generate a ``.jsonld`` test report as explained in [README.rst](./README.rst#tests)
 * Use the rdf_ tool to generate a ``.ttl``:
 
   * ``rdf serialize pyld-earl.jsonld --output-format turtle -o pyld-earl.ttl``
@@ -70,7 +68,7 @@ As of early 2020, the process to generate an EARL report for the official
 .. _JSON-LD Processor Conformance: https://w3c.github.io/json-ld-api/reports/
 .. _PEP 8 Style Guide: https://www.python.org/dev/peps/pep-0008/
 .. _Semantic Versioning: https://semver.org/
-.. _flake8: https://pypi.python.org/pypi/flake8
+.. _ruff: https://docs.astral.sh/ruff/
 .. _json-ld-api repository: https://github.com/w3c/json-ld-api/pulls
 .. _rdf: https://rubygems.org/gems/rdf
 .. _report instructions: https://github.com/w3c/json-ld-api/tree/master/reports