Bug 1500387 [wpt PR 13614] - remove duplicate line in docs for running the tests, a=testonly

Automatic update from web-platform-testsremove duplicate line
--

wpt-commits: 2b3e49da896ad67c8e337304a07a8c77f93b4c3e
wpt-pr: 13614

testing/web-platform/tests/docs/_running-tests/index.md

@@ -20,10 +20,10 @@ Or to run in a specified copy of Firefox:
 
     ./wpt run --binary ~/local/firefox/firefox firefox dom/historical.html
 
-`./wpt run --help` lists the supported products.
-
 For details on the supported products and a large number of other options for
-customising the test run, see `./wpt run --help`.
+customising the test run:
+
+    ./wpt run --help
 
 Additional browser-specific documentation: