docs: update unpkg installation to use latest version

[agilgur5]

Description

Discovered that the docs referred to an old version as part of argoproj/argo-workflows#12518

• this previously referred to 4.5.0, which was released 2 years ago

  • update to latest 5.11.0 instead

• also fix some formatting and style consistency issues

  • one meta tag was different from the rest
  • plus my editor auto-removed some trailing spaces

Motivation and Context

Use latest version in the docs instead of a 2 year old version

• somewhat important because some users wholesale copy+paste this code without modifications, such as in docs: Add Swagger UI to the API reference page argoproj/argo-workflows#10923
  • unlike the other installation methods, this will not install latest by default
  • alternatively, could change this to use to latest tag, although that is also an anti-pattern

How Has This Been Tested?

It's a pure docs change, so N/A
I did use part of this snippet in the above referenced Argo PR and I did manually test that the new version etc worked there

Screenshots (if appropriate):

n/a, pure docs change
Can see the rendered markdown in this PR

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[glowcloud]

LGTM!

[char0n]

Thank you for changes!