Update docs to use new .show behavior and clarify some copy for first example

Author: mdo

site/assets/scss/_component-examples.scss

@@ -206,10 +206,7 @@
 
   .offcanvas {
     position: static;
-    display: block;
     height: 200px;
-    visibility: visible;
-    transform: translateX(0);
   }
 }
 

site/content/docs/5.0/components/offcanvas.md

@@ -25,10 +25,10 @@ Offcanvas is a sidebar component that can be toggled via JavaScript to appear fr
 
 ### Offcanvas components
 
-Below is a _static_ offcanvas example (meaning its `position`, `display`, and `visibility` have been overridden). Offcanvas includes support for a header with a close button and an optional body class for some initial `padding`. We suggest that you include offcanvas headers with dismiss actions whenever possible, or provide an explicit dismiss action.
+Below is an offcanvas example that is shown by default (via `.show` on `.offcanvas`). Offcanvas includes support for a header with a close button and an optional body class for some initial `padding`. We suggest that you include offcanvas headers with dismiss actions whenever possible, or provide an explicit dismiss action.
 
-{{< example class="bd-example-offcanvas p-0 bg-light" >}}
-<div class="offcanvas offcanvas-start" tabindex="-1" id="offcanvas" aria-labelledby="offcanvasLabel">
+{{< example class="bd-example-offcanvas p-0 bg-light overflow-hidden" >}}
+<div class="offcanvas offcanvas-start show" tabindex="-1" id="offcanvas" aria-labelledby="offcanvasLabel" data-bs-backdrop="false">
   <div class="offcanvas-header">
     <h5 class="offcanvas-title" id="offcanvasLabel">Offcanvas</h5>
     <button type="button" class="btn-close text-reset" data-bs-dismiss="offcanvas" aria-label="Close"></button>