Normalize all links. (#24109)

* 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

2 files changed, 4 insertions, 4 deletions

diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 523282f2a8..c311dd691d 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -57,7 +57,7 @@ Good bug reports are extremely helpful, so thanks!
 
 Guidelines for bug reports:
 
-0. **Validate and lint your code** — [validate your HTML](https://html5.validator.nu)
+0. **Validate and lint your code** — [validate your HTML](https://html5.validator.nu/)
    and [lint your HTML](https://github.com/twbs/bootlint) to ensure your
    problem isn't caused by a simple error in your own code.
 
@@ -211,7 +211,7 @@ includes code changes) and under the terms of the
 * Push the revised version to your pull request's branch and post a comment on the pull request saying that you've fixed the problem(s). One of the Bootstrap Core Team members will then come along and reopen your pull request.
 * Or you can just open a new pull request for your revised version.
 
-[@twbs-savage](https://github.com/twbs-savage) is a Bootstrap bot that automatically runs cross-browser tests (via [Sauce](https://saucelabs.com) and Travis CI) on JavaScript pull requests. Savage will leave a comment on pull requests stating whether cross-browser JS tests passed or failed, with a link to the full Travis build details. If your pull request fails, check the Travis log to see which browser + OS combinations failed. Each browser test in the Travis log includes a link to a Sauce page with details about the test. On those details pages, you can watch a screencast of the test run to see exactly which unit tests failed.
+[@twbs-savage](https://github.com/twbs-savage) is a Bootstrap bot that automatically runs cross-browser tests (via [Sauce](https://saucelabs.com/) and Travis CI) on JavaScript pull requests. Savage will leave a comment on pull requests stating whether cross-browser JS tests passed or failed, with a link to the full Travis build details. If your pull request fails, check the Travis log to see which browser + OS combinations failed. Each browser test in the Travis log includes a link to a Sauce page with details about the test. On those details pages, you can watch a screencast of the test run to see exactly which unit tests failed.
 
 
 ## Code guidelines
diff --git a/.github/ISSUE_TEMPLATE.md b/.github/ISSUE_TEMPLATE.md
index d2a406f9c9..d9fc88e2b8 100644
--- a/.github/ISSUE_TEMPLATE.md
+++ b/.github/ISSUE_TEMPLATE.md
@@ -1,7 +1,7 @@
 Before opening an issue:
 
 - [Search for duplicate or closed issues](https://github.com/twbs/bootstrap/issues?utf8=%E2%9C%93&q=is%3Aissue)
-- [Validate](https://validator.w3.org/nu/) and [lint](https://github.com/twbs/bootlint#in-the-browser) any HTML to avoid common problems
+- [Validate](https://html5.validator.nu/) and [lint](https://github.com/twbs/bootlint#in-the-browser) any HTML to avoid common problems
 - Prepare a [reduced test case](https://css-tricks.com/reduced-test-cases/) for any bugs
 - Read the [contributing guidelines](https://github.com/twbs/bootstrap/blob/master/CONTRIBUTING.md)
 
@@ -14,7 +14,7 @@ When reporting a bug, include:
 
 - Operating system and version (Windows, Mac OS X, Android, iOS, Win10 Mobile)
 - Browser and version (Chrome, Firefox, Safari, IE, MS Edge, Opera 15+, Android Browser)
-- Reduced test cases and potential fixes using [JS Bin](https://jsbin.com)
+- Reduced test cases and potential fixes using [JS Bin](https://jsbin.com/)
 
 When suggesting a feature, include: