Improve configuration documentation

Edit existing content 📝

Improve Infection Monkey's documentation for configuration. Here are some recommendations:

Move the credentials page under features and give it an appropriate name.
Transform the relevant parts of import/export configuration page into a How To.
Transform the relevant parts of import/export configuration page into Explanation under features.
Transform the network page into an appropriate Explanation. Perhaps this should be part of the Agent Propagation Explanation.
Add a complete reference for the configuration (see #4210 for some information on how to do this).
Document any other features of interest using the appropriate type of documentation according to Diátaxis.