Implement text color changes across components

The commit involves modifications in various components to change 'text-gray-500' to 'text-muted-foreground'. The purpose of this change is to create uniformity in text colors across the application, enhancing the user interface's overall look and making color scheme tweaks easier in the future.

apps/web/app/(marketing)/docs/_components/docs-page-link.tsx

@@ -30,10 +30,7 @@ export function DocsPageLink({
 
       <span className={'flex flex-col space-y-1.5'}>
         <span
-          className={
-            'text-xs font-semibold uppercase dark:text-gray-400' +
-            ' text-gray-500'
-          }
+          className={'text-xs font-semibold uppercase text-muted-foreground'}
         >
           {before ? `Previous` : ``}
           {after ? `Next` : ``}