Fix docs and add nullcheck for ownedNumbers

[SecondeJK]

This fixes the documentation and adds a null check for adding a pattern to an OwnedNumbers filter.

Description

Added a new test to cover what is included in the docs for searching your own numbers in the Numbers API.

Motivation and Context

Bug fix.

How Has This Been Tested?

Test added.

Example Output or Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.