Add SPDX ID for Lab Materials

[tanto259]

Proposed changes

This PR adds SPDX ID and copyright statements for Lab Materials as suggested at the Project Charter, exceptions being the IBM-supplied JCL procedures (IGYWC, IGYWCL, IGYWCLG, and DSNUPROC).

Type of change

What type of changes does your PR introduce to the COBOL Programming Course? Put an x in the boxes that apply.

• [ ] 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)
• [X] Documentation (change which modifies documentation related to the course)
• [ ] This change requires an update to the course's z/OS environment

Checklist:

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• [X] I have read the Contributing Guideline
• [X] I have included a title and description for this PR
• [X] I have DCO-signed all of my commits that are included in this PR
• [X] 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)