Add documentation for mode: "frame" (#1131)

* Update pages.mdx

* copyedit

* correct functionality

* move frame beneath custom

---------

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>
Co-authored-by: Ethan Palm <[email protected]>

Author: mintlify[bot]

pages.mdx

@@ -82,6 +82,17 @@ mode: "custom"
 ---
 ```
 
+### Frame
+
+Frame mode provides a layout similar to custom mode, but preserves the sidebar navigation. This page mode allows for custom HTML and components while maintaining the default navigation experience. Frame mode is only available for Aspen and Almond themes.
+
+```yaml
+---
+title: "Frame page title"
+mode: "frame"
+---
+```
+
 ### Center
 
 Center mode removes the sidebar and table of contents, centering the content. This is useful for changelogs or other pages where you want to emphasize the content. Center mode is available for Mint and Linden themes.