Use https when possible.

docs/4.0/extend/icons.md

@@ -25,5 +25,5 @@ While we haven't tried these out, they do look promising and provide multiple fo
 - [Feather](https://feathericons.com/)
 - [Dripicons](http://demo.amitjakhu.com/dripicons/)
 - [Ikons](http://ikons.piotrkwiatkowski.co.uk/)
-- [Glyph](http://glyph.smarticons.co/)
+- [Glyph](https://glyph.smarticons.co/)
 - [Icons8](https://icons8.com/)

docs/4.0/getting-started/accessibility.md

@@ -50,7 +50,7 @@ Bootstrap includes support for the [`prefers-reduced-motion` media feature](http
 ## Additional resources
 
 - [Web Content Accessibility Guidelines (WCAG) 2.0](https://www.w3.org/TR/WCAG20/)
-- [The A11Y Project](http://a11yproject.com/)
+- [The A11Y Project](https://a11yproject.com/)
 - [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
 - [Tenon.io Accessibility Checker](https://tenon.io/)
 - [Colour Contrast Analyser (CCA)](https://developer.paciellogroup.com/resources/contrastanalyser/)

docs/4.0/getting-started/build-tools.md

@@ -28,7 +28,7 @@ Our [package.json]({{ site.repo }}/blob/v{{ site.current_version }}/package.json
 
 | Task | Description |
 | --- | --- |
-| `npm run dist` | `npm run dist` creates the `/dist` directory with compiled files. **Uses [Sass](http://sass-lang.com/), [Autoprefixer][autoprefixer], and [UglifyJS](https://github.com/mishoo/UglifyJS2).** |
+| `npm run dist` | `npm run dist` creates the `/dist` directory with compiled files. **Uses [Sass](https://sass-lang.com/), [Autoprefixer][autoprefixer], and [UglifyJS](https://github.com/mishoo/UglifyJS2).** |
 | `npm test` | Same as `npm run dist` plus it runs tests locally |
 | `npm run docs` | Builds and lints CSS and JavaScript for docs. You can then run the documentation locally via `npm run docs-serve`. |
 

docs/4.0/getting-started/download.md

@@ -60,7 +60,7 @@ npm install bootstrap
 
 Bootstrap's `package.json` contains some additional metadata under the following keys:
 
-- `sass` - path to Bootstrap's main [Sass](http://sass-lang.com/) source file
+- `sass` - path to Bootstrap's main [Sass](https://sass-lang.com/) source file
 - `style` - path to Bootstrap's non-minified CSS that's been precompiled using the default settings (no customization)
 
 ### RubyGems

docs/4.0/migration.md

@@ -80,7 +80,7 @@ Here are the big ticket items you'll want to be aware of when moving from v3 to
 ### Global changes
 
 - **Flexbox is enabled by default.** In general this means a move away from floats and more across our components.
-- Switched from [Less](http://lesscss.org/) to [Sass](http://sass-lang.com/) for our source CSS files.
+- Switched from [Less](http://lesscss.org/) to [Sass](https://sass-lang.com/) for our source CSS files.
 - Switched from `px` to `rem` as our primary CSS unit, though pixels are still used for media queries and grid behavior as device viewports are not affected by type size.
 - Global font-size increased from `14px` to `16px`.
 - Revamped grid tiers to add a fifth option (addressing smaller devices at `576px` and below) and removed the `-xs` infix from those classes. Example: `.col-6.col-sm-4.col-md-3`.