Add additional shields.io badges to README

[mitchelbaker-cisa]

🗣 Description

Add license, GitHub/PSGallery versions, CICD workflow, open issues, and GitHub/PSGallery download badges to the README with respective links.

💭 Motivation and context

Resolves #1166

🧪 Testing

• Check remote branch to see if badges display correctly, check links.
• Created fork and tested all badges display correctly in GitHub Pages.

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• PR targets the correct parent branch (e.g., main or release-name) for merge.
• Changes are limited to a single goal - eschew scope creep!
• Changes are sized such that they do not touch excessive number of files.
• All future TODOs are captured in issues, which are referenced in code comments.
• These code changes follow the ScubaGear content style guide.
• Related issues these changes resolve are linked preferably via closing keywords.
• All relevant type-of-change labels added.
• All relevant project fields are set.
• All relevant repo and/or project documentation updated to reflect these changes.
• Unit tests added/updated to cover PowerShell and Rego changes.
• Functional tests added/updated to cover PowerShell and Rego changes.
• All relevant functional tests passed.
• All automated checks (e.g., linting, static analysis, unit/smoke tests) passed.

✅ Pre-merge checklist

• PR passed smoke test check.

• Feature branch has been rebased against changes from parent branch, as needed

  Use Rebase branch button below or use this reference to rebase from the command line.

• Resolved all merge conflicts on branch

• Notified merge coordinator that PR is ready for merge via comment mention

✅ Post-merge checklist

• Feature branch deleted after merge to clean up repository.
• Verified that all checks pass on parent branch (e.g., main or release-name) after merge.
• Check that badges display correctly in GitHub Pages version of the README.

[james-garriss]

Perfect! Love it!

[buidav]

Good thing we only switched to mainly PSGallery once we hit 10K downloads for the package :)

[mitchelbaker-cisa]

Added a post-merge check to see if badges display correctly in GitHub Pages, as @james-garriss I believe the changes will only display after we push to main?

[james-garriss]

Correct. If you want to test before PR, you can clone repo, make changes to show the badge on its main, and see what happens.

[buidav]

On the current iteration of the PR. Would recommend putting the license badge somewhere after the GitHub release and PSGallery Badges.
As those are clickable release links and I suspect some people are savy enough to know they are. Lets save them several pixels of mouse drag :).

[mitchelbaker-cisa]

@nanda-katikaneni Ready to merge