put mdbook artifacts in root folder

[saraswatpuneet]

Problem

Fix MDBook deployed to gh-pages Link to GitHub Issue(s): https://github.com/LibertyDSNP/spec/issues/178 Solution

Updating deployment workflow to use the the static page artifacts in sub-directory of book generated by mdbook to gh-pages directory

Change summary:

• [x] Updated mdbook_cd workflow with this fix

• [x] Use the same deployment action for gh-pages as original deployment workflow
  Steps to Verify:

  1. Only way to verify would be to run the deployment and ensure we have all artifacts in root folder of gh-pages