[doc] Update environment variables in tests documentation

Add description for PYWIKIBOT_TEST_NO_RC and PYWIKIBOT_TEST_QUIET

Change-Id: I49e61b30d4c83473a35e5344afd9cdc1e28b7792
---
M tests/README.rst
1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/tests/README.rst b/tests/README.rst
index bff07ea..e6880d0 100644
--- a/tests/README.rst
+++ b/tests/README.rst
@@ -116,15 +116,28 @@
 
   .. note:: test names must be given without subsequent ``_tests``.
 
+**PYWIKIBOT_TEST_NO_RC**
+  This environment variable disables recent changes tests and can be used to
+  speed up tests. GitHub actions enables this setting for that purpose::
+
+    PYWIKIBOT_TEST_NO_RC=1
+
 **PYWIKIBOT_TEST_OAUTH**
   This environment variable holds the Oauth token. It is set by
   ``oauth_tests-ci.yml`` CI config file and is solely used by
   :mod:`tests.oauth_tests`. You can use it for your private tests. The
-  environment variabke must contain consumer key and secret and access
+  environment variable must contain consumer key and secret and access
   key and secret delimited by ``:`` as::
 
     PYWIKIBOT_TEST_OAUTH=consumer_key:consumer_secret:access_key:access:secret
 
+**PYWIKIBOT_TEST_QUIET**
+  This environment variable can be set for quit mode. It prevents output by
+  test package, i.e. 'max_retries reduced from x to y'. It is used be the
+  :func:`tests.utils.execute` test runner. To enable it for other tests use::
+
+        PYWIKIBOT_TEST_QUIET=1
+
 **PYWIKIBOT_TEST_RUNNING**
   This environment variable skips tests instead of raising
   :exc:`exceptions.MaxlagTimeoutError` when maximum retries attempted due to

