Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fix documentation errors across multiple files in the cFS bundle: broken links, typos, incorrect git instructions, stale references, and missing content.

Changes:

• README.md: Fix broken cFS Overview PDF link, master→main branch ref, add missing cFS_LIB description, add Skeleton App to distributions list
• CONTRIBUTING.md: Fix git merge→git checkout in squash instructions, fix duplicate step numbering (3→4), fix "had"→"has" grammar
• .github/workflows/README.md: Fix codeql-build.yml→codeql-analysis.yml badge
• .github/ISSUE_TEMPLATE/bug_report.md: Update outdated version examples (cFE 6.6→7.0.0)
• .github/pull_request_template.md: Update outdated version examples (cFE 6.6→7.0.0)
• SECURITY.md: Fix "is ran"→"is run" grammar (×2)

Testing performed

1. Verified all updated links resolve correctly
2. Reviewed all changes for accuracy against live GitHub repos

Expected behavior changes
No impact to behavior documentation only changes.

System(s) tested on

• N/A (documentation only)

Additional context
None.

NOTE:-
CLA already signed and sent for previous PR(s).