When mermaid starts configuration is extracted to a configuration to be used for a diagram. There a 3 sources for configuration:
* The default configuration
* Overrides on the site level, set is set by the initialize call and will be applied for all diagrams in the site/app. The term for this is the **siteConfig**.
* Directives - diagram authors can update select configuration parameters directly int they diagram code via directives and these are applied to the render config.
This method resets the configuration for a diagram to the site configuration, the configuration provided by the site integrator. Before each rendering of a diagram reset is called in the very beginning of render.