Better documentation for tests

[jfavellar90]

After checking a bit more the content of the repo, I think we need to put extra efforts in the following items:

• Highlight the relevance of the AUTOMATIC_AUTH_FOR_TESTING feature flag to simplify the test.
• Better description of the options available in the PROFILE files.
• Better description of the tests available.
• Indicate the dependency on chromium to execute Browser tests.
• Do we really need node.js for development purposes?