Bug 1753413 - add rst to the file-whitespace linter r=andi

And add testing/perfdocs/generated/ to the ignore list

Differential Revision: https://phabricator.services.mozilla.com/D137742

tools/lint/file-whitespace.yml

@@ -131,6 +131,7 @@ file-whitespace:
         - testing/mozharness/configs/raptor/linux64_config_taskcluster.py
         - testing/mozharness/configs/talos/linux64_config_taskcluster.py
         - testing/mozharness/configs/web_platform_tests/test_config_windows.py
+        - testing/perfdocs/generated/
         - testing/talos/talos/cmanager_base.py
         - testing/talos/talos/pageloader/chrome/pageloader.xhtml
         - testing/talos/talos/tests
@@ -198,6 +199,7 @@ file-whitespace:
         - .py
         - .properties
         - .rs
+        - .rst
         - .xhtml
     support-files:
         - 'tools/lint/file-whitespace/**'