Fixes #19267: Mention grid class changes in migration docs

diff --git a/docs/migration.md b/docs/migration.md
index 48f1178e02fe9a1eb9a8c7a7b1df565032e916c5..8fea84b8003cfcf5d0e77708fe1c5aff60d99ec0 100644 (file)
--- a/docs/migration.md
+++ b/docs/migration.md
@@ -116,6 +116,9 @@ New to Bootstrap 4 is the Reboot, a new stylesheet that builds on Normalize with
 ### Grid system
 
 - Added a new `~480px` grid breakpoint, meaning there are now five total tiers.
+- Renamed the responsive grid modifier classes from `.col-{breakpoint}-{modifier}-{size}` to `.{modifier}-{breakpoint}-{size}` for simpler grid classes. For example, instead of `.col-md-3.col-md-push-9` it's `col-md-3.push-md-9`.
+- Overhauled the grid mixins to merge `make-col` and `make-col-span` into a single `make-col` mixin, thereby ensuring mixins and predefined classes utilize the same float/flex behaviors.
+- Added flexbox utility classes for grid system and components.
 
 ### Navs