Implementation of `UnitRegistryIntroComponent` class that creates a part of a report

[bogumilchilinski]

Class is to implement in guide.en.py module that creates a part (reporting component - formally child of ReportComponent class) of guide for reporting module.

[amvdek]

Class was checked by the following call:

from dynpy.utilities.components.guides.en import UnitRegistryIntroComponent
UnitRegistryIntroComponent(None);