[docs] Capitalize Material Design on the Breakpoints page (mui#34481)

Signed-off-by: Dustin-Digitar <113573618+Dustin-Digitar@users.noreply.github.com>

docs/data/material/customization/breakpoints/breakpoints.md

@@ -2,7 +2,7 @@
 
 <p class="description">API that enables the use of breakpoints in a wide variety of contexts.</p>
 
-For optimal user experience, material design interfaces need to be able to adapt their layout at various breakpoints.
+For optimal user experience, Material Design interfaces need to be able to adapt their layout at various breakpoints.
 MUI uses a **simplified** implementation of the original [specification](https://material.io/design/layout/responsive-layout-grid.html#breakpoints).
 
 The breakpoints are used internally in various components to make them responsive,