[docs] Devdocs Bootstrap forms refactor

docs/devupdate.md

@@ -7,7 +7,7 @@ tags:
 
 <!-- markdownlint-disable no-inline-html -->
 
-import { Since } from '@site/src/components';
+import { Since, ValidExample, InvalidExample } from '@site/src/components';
 
 This page highlights the important changes that are coming in Moodle 4.4 for developers.
 
@@ -62,6 +62,39 @@ shortname,fullname,category,summary,cohort,student,cohort,teacher
 
 </details>
 
+## Bootstrap preparations for version 5
+
+<Since version="4.4" issueNumber="MDL-71979" />
+
+Some of the Bootstrap 4 classes will be deprecated or dropped in its version 5. To prepare for this, some of the current Bootstrap 4 classes usages have been replaced with version 5 compatible classes. This will help us to upgrade to Bootstrap 5 in the future.
+
+- The `.form-group` helper class has been replaced with margins.
+- The `.form-inline` helper class has been replaced with utility classes.
+
+<InvalidExample title="Don't">
+
+```html
+<form class="form-inline">
+    <div class="form-group">
+        [...]
+    </div>
+</form>
+```
+
+</InvalidExample>
+
+<ValidExample title="Do">
+
+```html
+<form class="d-flex flex-wrap align-items-center">
+    <div class="mb-3">
+        [...]
+    </div>
+</form>
+```
+
+</ValidExample>
+
 ## Previous versions
 
 - [Moodle 4.3 developer update](./4.3/devupdate)