Update themes.mdx

Author: mintlify[bot]

themes.mdx

@@ -34,7 +34,7 @@ export const ThemeCard = ({ title, value, description, href }) => {
 <div className="pt-10 pb-24 px-4 px-4 max-w-3xl mx-auto prose prose-gray">
   <label className="eyebrow h-5 text-primary dark:text-primary-light text-sm font-semibold">Core Concepts</label>
   <h1 className="mt-1 mb-2 text-2xl sm:text-3xl text-gray-900 tracking-tight dark:text-gray-200 font-semibold">Themes</h1>
-  <label className="text-lg prose prose-gray dark:prose-invert">Custom the appearance of your documentation<br /><br />Configure [theme](settings#param-theme) in docs.json using one of the following themes.</label>
+  <label className="text-lg prose prose-gray dark:prose-invert">Customize the appearance of your documentation<br /><br />Configure [theme](settings#param-theme) in docs.json using one of the following themes.</label>
 
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