Update to fix sidebar over text (microsoft#5567)

- [x] Needs to be tested.

Fixes microsoft#5494.

Sample screenshot:
<img width="1141" alt="image"
src="https://github.com/microsoft/DeepSpeed/assets/114770087/f89f642b-bca1-4d45-b3f1-ec7943ab2ad4">

docs/_sass/minimal-mistakes/_sidebar.scss

@@ -79,6 +79,7 @@
     top: auto;
     right: 0;
     width: $right-sidebar-width-narrow;
+    margin-right: -1.5 * $right-sidebar-width-narrow;
     padding-left: 1em;
     z-index: 10;
 
@@ -93,6 +94,7 @@
 
   @include breakpoint($x-large) {
     width: $right-sidebar-width;
+    margin-right: -1.5 * $right-sidebar-width-narrow;
   }
 }