Add scenario from connector to main introduction

[sparrell]

Is your feature request related to a problem? Please describe.
I'm always frustrated when newbies can't figure out what is going on in an project and the overview jumps from 50,000 feet to below sea level on the intro page.
In particular I think https://github.com/opencybersecurityalliance/stix-shifter/blob/master/OVERVIEW.md#why-would-i-want-to-use-this needs some "for example".

Describe the solution you'd like
The https://github.com/opencybersecurityalliance/stix-shifter/blob/master/adapter-guide/develop-stix-adapter.md page has a good example and the first two sections (https://github.com/opencybersecurityalliance/stix-shifter/blob/master/adapter-guide/develop-stix-adapter.md#participants and https://github.com/opencybersecurityalliance/stix-shifter/blob/master/adapter-guide/develop-stix-adapter.md#problem-to-solve) could get added to https://github.com/opencybersecurityalliance/stix-shifter/blob/master/OVERVIEW.md#why-would-i-want-to-use-this. Things clicked much better for me once I read these two sections.

As a separate aside - you might want to make 'documentation' a peer to bug/feature in issues. I agree documentation is part of the product (so everything, including documentation, is a bug or a feature) but still might be better separate (eg was this issue a bug -newbie had trouble understanding - or a feature - improve documentation).

[delliott90]

That's a great idea. We can always improve our documents. Created a new label as suggested.