Add GitHub Pages deployment for DocC documentation

[Copilot]

Repository lacks public documentation hosting for prospective users to preview API docs.

Changes

Package.swift

• Bump swift-tools-version 5.3 → 5.6 for plugin support
• Add swift-docc-plugin dependency

.github/workflows/deploy-docs.yml (new)

• Build DocC on macOS with static hosting transformation
• Deploy to GitHub Pages on master branch push
• Set --hosting-base-path TimeIt for correct asset paths

README.md

• Add link to hosted docs at https://mikelrob.github.io/TimeIt/documentation/timeit/

Post-merge setup required

Enable GitHub Pages in repository settings, set source to "GitHub Actions". First deployment will run automatically.

Original prompt

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This section details on the original issue you should resolve

<issue_title>No GitHub pages</issue_title>
<issue_description>This repo doesn't have a GitHub pages pages. It should have it's docs deployed to GitHub pages for prospective users to preview.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes No GitHub pages #5

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