Upgrade markdown-it-anchor to 5.0.0 and fix anchor tag scrolling

[Xenonym]

What is the purpose of this pull request? (put "X" next to an item, remove the rest)
• [X] Bug fix

Part of #413.

What is the rationale for this request?
[email protected] creates anchor tags with URL encoded characters when the heading contains special characters. For example, "Guideline: Avoid Unsafe Shortcuts" becomes guideline%3A-avoid-unsafe-shortcuts. This breaks the use of jQuery to scroll to the correct anchor as jQuery will not be able to locate elements with special characters in the id. This can be fixed by using document.getElementById to locate the element instead.

What changes did you make? (Give an overview)
Upgrade markdown-it-anchor to ^5.0.0 and use document.getElementById to locate the element to scroll to instead of jQuery.

Provide some example code that this change will affect:

## Guideline: Avoid Unsafe Shortcuts

Testing instructions:

1. Create a markdown document with headers that have special characters eg. :. The anchor link should be able to scroll normally despite being generated from [email protected].

[yamgent]

Thanks, looks good now.

Please squash the PR to two commits:

• Upgrade markdown-it-anchor to 5.0.0: Should contain the package.json, package-lock.json, and the change in the anchors for the html files.
• Fix URL anchor scrolling: Should contain the changes in setup.js.

On a side note, I edited your initial post, because using the word "Resolve" will close the issue #413, but in this case the issue needs to be fixed on two different projects (this PR fixes one of them), so the issue shouldn't be closed yet. But you don't have to worry about the other project for now (it is a trivial fix), so this PR is basically complete.

[Xenonym]

Thanks for the review and comments @yamgent! I have squashed the commits as requested. Noted on the other project as well.