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

_data/browser-features.yml

@@ -52,7 +52,7 @@
   browser: >
     Edge
   summary: >
-    Implement the [`of <selector-list>` clause](http://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
+    Implement the [`of <selector-list>` clause](https://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
   upstream_bug: >
     UserVoice#15944476
   origin: >
@@ -62,7 +62,7 @@
   browser: >
     Firefox
   summary: >
-    Implement the [`of <selector-list>` clause](http://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
+    Implement the [`of <selector-list>` clause](https://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
   upstream_bug: >
     Mozilla#854148
   origin: >
@@ -102,7 +102,7 @@
   browser: >
     Chrome
   summary: >
-    Implement the [`of <selector-list>` clause](http://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
+    Implement the [`of <selector-list>` clause](https://caniuse.com/#feat=css-nth-child-of) of the `:nth-child()` pseudo-class
   upstream_bug: >
     Chromium#304163
   origin: >

_data/showcase.yml

@@ -9,7 +9,7 @@
   img: vogue
 
 - name: Riot Design
-  url: http://riotdesign.eu/en/
+  url: https://riot.design/en/
   expo_url: https://expo.getbootstrap.com/2014/03/13/riot-design/
   img: riot