docs(material/slider): value should go in the input tag (#28257)

* src/material/slider/slider.md

* slider

* slider

* docs(material/slider): value should go in the input tag

* docs(material/slider): value should go in the input tag

(cherry picked from commit 1999e20)

Author: mruanova

src/material/slider/slider.md

@@ -10,8 +10,8 @@ in increments of `1`. These values can be changed by setting the `min`, `max`, a
 respectively. The initial value is set to the minimum value unless otherwise specified.
 
 ```html
-<mat-slider min="1" max="5" step="0.5" value="1.5">
-  <input matSliderThumb>
+<mat-slider min="1" max="5" step="0.5">
+  <input matSliderThumb value="1.5">
 </mat-slider>
 ```