Add Additional Exercise to Lab 8.6: Count Clients from a Different State

[oathar]

Proposed changes

This PR adds a hands-on exercise to the lab 8.6 involving CBL0006 and CBL0006J. The original program counts clients from Virginia. This exercise challenges learners to update the logic to count clients from a different state (e.g., New York), encouraging deeper understanding of conditional filtering, working-storage layout, and output formatting in COBOL.

The goal is to move students away from simple copy-paste behavior and encourage them to read, reason, and modify code thoughtfully. Lab hints and complete solution code (CBL0006C) have been included.

Fixes # N/A (new enhancement)

Type of change

What type of changes does your PR introduce to the COBOL Programming Course?

• Bug fix (change which fixes one or more issues)
• New feature (change which adds functionality or features to the course)
• Translations (change which adds or modifies translations of the course)
• Documentation (change which modifies documentation related to the course)
• This change requires an update to the course's z/OS environment

Checklist:

• I have read the Contributing Guideline
• I have included a title and description for this PR
• I have DCO-signed all of my commits that are included in this PR
• I have tested it manually and there are no regressions found
• I have commented my code, particularly in hard-to-understand areas (if appropriate)
• I have made corresponding changes to the documentation (if appropriate)