Refreshing GettingStarted ServiceMatrix article

Updated with code and image corrections.
Typo repair in SM Gettingstarted

Updates to content.
Fixed index numbering SM getting started.
Updated SM Getting Started Pub Sub

Update links images, code, etc. for new ServiceMatrix changes.
Added Using ServiceMatrix code to the menu

Added to the menu and index the article customizing-extending.md
Updated ServiceMatrix Full Duplex Saga Example

Fixed all the diagrams and code blocks to the current SM version and
approach, naming, etc.
Updated Customizing-Extending ServiceMatrix

Updated for new code style and naming convention of handlers.
Updated Diagram for ServiceMatrix ServiceInsight

Flow diagram had incorrect code naming convention.
Updating Getting Started ServiceMatrix

The New Service button has been removed.  It was used in the guide and
visible in the screenshots.
Minor content and image rpr in SM getting started

Fixed type and one more image.