fix(material-experimental/mdc-dialog): expose dialog-legacy-padding mixin

Exposes the `dialog-legacy-padding` mixin which seems to be not
accessible in the primary Sass entry-point, but being mentioned in the docs.

Author: devversion

src/material-experimental/_index.scss

@@ -71,3 +71,6 @@
   mdc-tabs-density, mdc-tabs-theme;
 @forward './mdc-tooltip/tooltip-theme' as mdc-tooltip-* show mdc-tooltip-color,
   mdc-tooltip-typography, mdc-tooltip-density, mdc-tooltip-theme;
+
+// Additional public APIs for individual components
+@forward './mdc-dialog/dialog-legacy-padding' as mdc-dialog-* show mdc-dialog-legacy-padding;

src/material-experimental/mdc-dialog/README.md

@@ -3,6 +3,7 @@ This is a prototype of an alternate version of `MatDialog` built on top of
 experimental and should not be used in production.
 
 ## How to use
+
 Assuming your application is already up and running using Angular Material, you can add this
 component by following these steps:
 
@@ -67,7 +68,7 @@ directly through CSS, or move them into one of the defined sections the Angular
 provides.
 
 ```scss
-@use '@angular/material-experimental/mdc-dialog/dialog-legacy-padding' as mat-mdc-dialog;
+@use '@angular/material-experimental' as experimental;
 
-@include mat-mdc-dialog.legacy-padding();
+@include experimental.mdc-dialog-legacy-padding();
 ```