Reorganize docs for easier deploys

With the current docs directory setup, I'm making too many mistakes and have to manually address path changes and directory moves on deploy. This makes for a frustrating experience developing locally and shipping releases. With this PR, we're basically back to the same setup from v3—duplicating the dist directory into our docs directory. Not the most ideal, but very straightforward for me as the release manager.

site/docs/4.1/utilities/shadows.md

@@ -0,0 +1,19 @@
+---
+layout: docs
+title: Shadows
+description: Add or remove shadows to elements with box-shadow utilities.
+group: utilities
+toc: false
+---
+
+## Examples
+
+While shadows on components are disabled by default in Bootstrap and can be enabled via `$enable-shadows`, you can also quickly add or remove a shadow with our `box-shadow` utility classes. Includes support for `.shadow-none` and three default sizes (which have associated variables to match).
+
+{% capture example %}
+<div class="shadow-none p-3 mb-5 bg-light rounded">No shadow</div>
+<div class="shadow-sm p-3 mb-5 bg-white rounded">Small shadow</div>
+<div class="shadow p-3 mb-5 bg-white rounded">Regular shadow</div>
+<div class="shadow-lg p-3 mb-5 bg-white rounded">Larger shadow</div>
+{% endcapture %}
+{% include example.html content=example %}