Revisit the structure of the documentation #1157
Description
For example, logging's configuration is not addressed at all in "Configuring ReFrame For Your Site" section, but it is only addressed in "Running ReFrame". Also how the user navigates through the documentation should be rethought as well. There could be multiple levels of tutorials that will build gradually on more complex use cases, but we should also have complete references for the configuration and the command-line interface as well.