Add Product Analytics to GDK how-to docs

What does this merge request do and why?

This MR copies the snippet information we've been passing around for the How to set up and validate locally step within groupproduct analytics MRs and adds it to the GDK to make it more discoverable and more easily shared.

Impacted categories

The following categories relate to this merge request:

• [-] gdk-reliability - e.g. When a GDK action fails to complete.
• [-] gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• [-] gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• [-] Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• [-] Announcement added, if change is notable.
• [-] gdk doctor test added, if needed.
• [-] Add the ~highlight label if this MR should be included in the CHANGELOG.md.