Docs not deployed when PR is merged to main

[astrogeco]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I performed a cursory search to see if the bug report is relevant, not redundant, nor in conflict with other tickets.

Describe the bug

The skip duplicates check catches the "same content" from pull requests and thus isn't being triggered by a push to main.

To Reproduce

See workflow runs related to IC: Caelum-rc4+dev8.

https://github.com/nasa/cFS/actions/runs/2192037376, push to main, skipped due to run in PR #461 https://github.com/nasa/cFS/actions/runs/2191974505

Expected behavior

Always run the documentation job on a push to main.

Proposed Solution

Skip the "check-for-duplicates" step in pushes to main branch.

System observed on:
Github actions

Additional context
n/a

Reporter Info
Gerardo E. Cruz-Ortiz, NASA