fix docs

docs/components/tree.md

@@ -287,7 +287,7 @@ const App = () => {
 };
 ```
 
-### Custom expand/collapse icons
+### Customizing the Expand and Collapse Icons
 
 Use the `expand-icon` and `collapse-icon` slots to change the expand and collapse icons, respectively.
 
@@ -398,11 +398,11 @@ Decorative icons can be used before labels to provide hints for each node.
       </sl-tree-item>
       <sl-tree-item>
         <sl-icon name="file-pdf"></sl-icon>
-        final.pdg
+        final.pdf
       </sl-tree-item>
       <sl-tree-item>
         <sl-icon name="file-bar-graph"></sl-icon>
-        sales.txt
+        sales.xls
       </sl-tree-item>
     </sl-tree-item>
   </sl-tree-item>