docs: add CLI v0.28.1 changelog entry (#475)

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

Author: factory-ben

docs/changelog/cli-updates.mdx

@@ -4,6 +4,22 @@ description: "Recent features and improvements to Factory CLI"
 rss: true
 ---
 
+<Update label="December 2" rss={{ title: "CLI Updates", description: "Certificate caching, image upload limits, and settings rendering fixes" }}>
+  `v0.28.1`
+
+  ## Improvements
+
+  * **Certificate caching** - Certificates are now cached on startup for faster loading
+  * **Image upload limits** - Conversation images are now limited to prevent 413 errors when uploading large images
+  * **MCP registry helper** - Added note for STDIO servers in MCP registry explaining installation requirements
+
+  ## Bug fixes
+
+  * Fixed invalid signature in thinking block after assistant message interrupt
+  * Fixed settings menu not showing all options when loading asynchronously
+
+</Update>
+
 <Update label="December 1" rss={{ title: "CLI Updates", description: "Session management, slash command navigation, thinking improvements, and Figma MCP support" }}>
   `v0.28.0`