Create a Troubleshooting page on Knowledgebase

[robertbindar]

We should have a documentation page where we describe all possible errors that occur when bad things happen in the kernel.
This is extremely useful for the errors that happen during the startup phase of the kernel, when for instance the kernel detects that there is no MariaDB installed on the system. Such errors happening during startup can only displayed in the terminal window because the kernel, AFAIK, is capable of displaying errors inside the notebook frontend only when a cell is executed. So for such startup errors, the user will have to look into the terminal logs, we should document those to make them less confusing.