Add Documentation for Static Reachability Feature

Static Reachability Feature

We are introducing a new experimental feature called Static Reachability. This feature allows users to assess the reachability of sbom packages found in the customer's repository .

At start , this feature will be experimental , Which require adding a new Env variable to turn on the feature, In addition we will support Java and Python only at this stage.

Note: This documentation will be updated with more information as the feature evolves