Fix code block syntax in Reusable Markdown page (#166)

Author: devalog

fern/products/docs/pages/component-library/custom-components/reusable-markdown.mdx

@@ -34,15 +34,17 @@ To use a snippet in your documentation, reference it by its file path (including
 
 <Tabs>
     <Tab title="Markdown">
-        ```mdx
+    
+        ```jsx
         Peace lilies are easy to grow and relatively trouble-free.
 
-        <Markdown src="/snippets/peace-lily.mdx" />
+        <Markdown src="/snippets/peace-lily.mdx">
         ```
+
     </Tab>
     <Tab title="Preview">
         Peace lilies are easy to grow and relatively trouble-free.
-
+        
         <Markdown src="/snippets/peace-lily.mdx" />
     </Tab>
 </Tabs>