Improves forms migration guide, docs, and scss (#24348)

* fixes migration forms guides

* removes container from Horizontal form

* adds col-form-label sizes on form docs

* removes .form-control-label from forms.scss

* add note to migration

1 files changed, 3 insertions, 2 deletions

diff --git a/docs/4.0/migration.md b/docs/4.0/migration.md
index 5274e3c4b..bad3738a2 100644
--- a/docs/4.0/migration.md
+++ b/docs/4.0/migration.md
@@ -18,6 +18,7 @@ While in beta, we aim to have no breaking changes. However, things don't always
 - Responsive tables now generate classes for each grid breakpoint. This breaks from Beta 1 in that the `.table-responsive` you've been using is more like `.table-responsive-md`. You may now use `.table-responsive` or `.table-responsive-{sm,md,lg,xl}` as needed.
 - Dropped Bower support as the package manager has been deprecated for alternatives (e.g., Yarn or npm). [See bower/bower#2298](https://github.com/bower/bower/issues/2298) for details.
 - Bootstrap now requires jQuery 3.0.0 or higher.
+- Removed the unused `.form-control-label` class. If you did make use of this class, it was duplicate of the `.col-form-label` class that vertically centered a `<label>` with it's associated input in horizontal form layouts.
 - Changed the `color-yiq` from a mixin that included the `color` property to a function that returns a value, allowing you to use it for any CSS property. For example, instead of `color-yiq(#000)`, you'd write `color: color-yiq(#000);`.
 
 ### Highlights
@@ -110,7 +111,7 @@ New to Bootstrap 4 is the [Reboot]({{ site.baseurl }}/docs/{{ site.docs_version
 ### Forms
 
 - Moved element resets to the `_reboot.scss` file.
-- Renamed `.control-label` to `.form-control-label`.
+- Renamed `.control-label` to `.col-form-label`.
 - Renamed `.input-lg` and `.input-sm` to `.form-control-lg` and `.form-control-sm`, respectively.
 - Dropped `.form-group-*` classes for simplicity's sake. Use `.form-control-*` classes instead now.
 - Dropped `.help-block` and replaced it with `.form-text` for block-level help text. For inline help text and other flexible options, use utility classes like `.text-muted`.
@@ -119,7 +120,7 @@ New to Bootstrap 4 is the [Reboot]({{ site.baseurl }}/docs/{{ site.docs_version
 - Horizontal forms overhauled:
   - Dropped the `.form-horizontal` class requirement.
   - `.form-group` no longer applies styles from the `.row` via mixin, so `.row` is now required for horizontal grid layouts (e.g., `<div class="form-group row">`).
-  - Added new `.form-control-label` class to vertically center labels with `.form-control`s.
+  - Added new `.col-form-label` class to vertically center labels with `.form-control`s.
   - Added new `.form-row` for compact form layouts with the grid classes (swap your `.row` for a `.form-row` and go).
 - Added custom forms support (for checkboxes, radios, selects, and file inputs).
 - Replaced `.has-error`, `.has-warning`, and `.has-success` classes with HTML5 form validation via CSS's `:invalid` and `:valid` pseudo-classes.