Add notes on fixing broken ONL installs, and spelling fixes

Change-Id: I7ebe12fc579347e5f9aea706cc9f7ce029bcec5e
diff --git a/testing/sdcore_testing.rst b/testing/sdcore_testing.rst
index 535a1ad..22b5f3a 100644
--- a/testing/sdcore_testing.rst
+++ b/testing/sdcore_testing.rst
@@ -138,7 +138,7 @@
 1. `omec_deploy_dev`: this job executes the scalability test suite.
 2. `robotframework-test_dev`: this job is similar to `ng40-test_dev` with the
    exception that instead of directly executing NG40 commands it calls robot
-   framework to exectue the test cases and publishes the test results using
+   framework to execute the test cases and publishes the test results using
    `RobotPublisher` Jenkins plugin. The robot results will also be copied to
    the upstream job and published there.
 3. `archive-artifacts_dev`: this job collects and uploads k8s and container logs.