* use a trailing slash when possible
* use https when possible
* remove a few redirected links
* consistently use `https://popper.js.org/`
* fix `iconUrl` in nuget files
* change Jekyll Windows guide to the official one

normalize is no longer part of BS

Closes #20165

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Refs https://github.com/blog/2119-add-reactions-to-pull-requests-issues-and-comments
Refs https://github.com/dear-github/dear-github/issues/141#issuecomment-195106918
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Refs #19192
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Adding Microsoft Edge and the rendering engine EdgeHTML.

Closes #18303
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provide V4 JSBin template for users to use when sending bug reports.

As Slack is a common replacement for IRC for projects (e.g. Wordpress), I propose that we encourage the use of Slack as you have members of the core team using it while IRC often does not have any of the core team available.

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Refs #12352, which is now implemented & deployed.
More info: https://github.com/twbs/savage

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Based on https://github.com/twbs/rorschach/tree/master/docs

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Fixes https://github.com/twbs/bootlint/issues/67

Thanks to @collinanderson
Closes #14567

Refs: #14109

Fixes #12657