Doc previews on pull request, build on merge

[Espeer5]

Preview docs on pull request

Description:

This sets up the workflows such that doc previews which do not change the main doc pages are deployed on the creation of a pull request for review, and when the PR is actually merged, we deploy to the main docs pages.

Content

• Adds a new workflow for creating doc previews
• Edits the pages deployment workflow to be triggered only on pushes to the main branch

Related issues

• 18

Todo

• [x] Verify that the preview workflow is working by viewing the preview created by this PR

[github-actions[bot]]

PR Preview Action v1.4.4 :---: :rocket: Deployed preview to https://Espeer5.github.io/Trinary/pr-preview/pr-19/ on branch gh-pages at 2023-08-03 19:57 UTC