[DOCS]: Add "getting started" page

[andrewedstrom]

Documentation Request

Packages related to documentation request:

• OWL/SHACL definitions
• ts-sdk
• ts-etl
• spa

Description

As a person trying to use the docmaps-sdk to parse docmaps, when I go to the documentation it would be nice to see a "Getting started" page that shows me the basic functionality of the SDK, such as parsing/validating a Docmap and handling an error.

Additional information

N/A