Closes #2525

This PR provides an almost complete rewrite of the current Configuration page, based on these principles:

• every example of configuration file (except those that apply only to a single format) is provided in all standard configuration formats,
• the page is sorted so that the syntax of the configuration file is provided first, followed by the most commonly used elements. Advanced settings are either at the end of the page or on separate pages.

Most notably:

• the Configuration properties and Scripts are rarely used (except log4j2.configurationFile), so they are moved to a separate page,
• the Chainsaw can automatically process your log files (Advertising appender configurations) section is removed since Chainsaw is a dormant project,
• the Status Messages section is removed, since this should be part of the Log4j API and Troubleshooting pages that are currently being revamped.

We also sort the chapters contained in the Manual, so that the chapters dealing with configuration are close to each other.