migration.md: use https.

site/docs/4.2/migration.md

@@ -115,7 +115,7 @@ Here are the big ticket items you'll want to be aware of when moving from v3 to
   - [Font Awesome](https://fontawesome.com/)
   - See the [Extend page]({{ site.baseurl }}/docs/{{ site.docs_version }}/extend/icons/) for a list of alternatives. Have additional suggestions? Please open an issue or PR.
 - **Dropped the Affix jQuery plugin.**
-  - We recommend using `position: sticky` instead. [See the HTML5 Please entry](http://html5please.com/#sticky) for details and specific polyfill recommendations. One suggestion is to use an `@supports` rule for implementing it (e.g., `@supports (position: sticky) { ... }`)
+  - We recommend using `position: sticky` instead. [See the HTML5 Please entry](https://html5please.com/#sticky) for details and specific polyfill recommendations. One suggestion is to use an `@supports` rule for implementing it (e.g., `@supports (position: sticky) { ... }`)
   - If you were using Affix to apply additional, non-`position` styles, the polyfills might not support your use case. One option for such uses is the third-party [ScrollPos-Styler](https://github.com/acch/scrollpos-styler) library.
 - **Dropped the pager component** as it was essentially slightly customized buttons.
 - **Refactored nearly all components** to use more un-nested class selectors instead of over-specific children selectors.