add code block styling in global settings (#303)

Author: dks333

settings/global.mdx

@@ -201,6 +201,16 @@ settings. Learn more about the [properties](#properties) or from an
   The style of the rounded edges.
 </ResponseField>
 
+<ResponseField name="codeBlock" type="CodeBlock">
+  The style of the code block.
+  <Expandable title="CodeBlock">
+    <ResponseField name="mode" type={'"dark" | "auto"'} default="dark">
+      `auto` will automatically switch between light and dark mode based on the
+      user's system preferences.
+    </ResponseField>
+  </Expandable>
+</ResponseField>
+
 ### Structure
 
 <ResponseField name="navigation" type="Navigation[]" required>