Issue #90 - Error Suite 'Tests' contains no tests

Updated the troubleshooting section

Author: ppodgorsek

README.md

@@ -108,6 +108,24 @@ In case further investigation is required, the logs can be accessed by mounting
 * Linux/Mac: ``-v `pwd`/logs:/var/log:Z``
 * Windows: ``-v ${PWD}/logs:/var/log:Z``
 
+### Error Suite contains no tests
+
+When running tests, an unexpected error sometimes occurs:
+
+> [Error] Suite contains no tests.
+
+There are two main causes to this:
+* Either the test folder is not the right one,
+* Or the permissions on the test folder are too restrictive.
+
+As there can sometimes be issues as to where the tests are run from, make sure the correct folder is used by trying the following actions:
+* Use a full path to the folder instead of a relative one,
+* Replace any`` `pwd` ``or `${PWD}` by the full path to the folder.
+
+It is also important to check if Robot Framework is allowed to access the resources it needs, i.e.:
+* The folder where the tests are located,
+* The test files themselves.
+
 ## Please contribute!
 
 Have you found an issue? Do you have an idea for an improvement? Feel free to contribute by submitting it [on the GitHub project](https://github.com/ppodgorsek/docker-robot-framework/issues).