Improve spacing docs

Author: reinink

docs/source/docs/spacing.blade.md

@@ -31,6 +31,7 @@ For example, `.pt-2` would add `.5rem` of padding to the top of the element, `.m
     </div>
     <div class="pl-12 pr-12 border-l">
         <div class="mb-3 text-slate"><span class="uppercase">Side</span> <span class="text-slate-light text-xs">(optional)</span></div>
+        <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded bg-smoke-light">&nbsp;</code> All</div>
         <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded">t</code> Top</div>
         <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded">r</code> Right</div>
         <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded">b</code> Bottom</div>
@@ -48,5 +49,6 @@ For example, `.pt-2` would add `.5rem` of padding to the top of the element, `.m
         <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded">6</code> 1.5rem</div>
         <div><code class="inline-block my-1 mr-1 px-2 py-1 font-mono border rounded">8</code> 2rem</div>
         <div><code class="inline-block my-1 mr-1 px-1 py-1 font-mono border rounded">px</code> 1px</div>
+        <div><code class="inline-block my-1 mr-1 px-1 py-1 font-mono border rounded">auto</code> auto <span class="text-slate-light text-xs">(horizontal margins only)</span></div>
     </div>
 </div>