chore: fix upload instructions text for clarity (#98)

Author: juliangruber

src/components/file-picker/upload-instructions.tsx

@@ -21,7 +21,7 @@ export function UploadInstructions({ maxSize, ...rest }: UploadInstructionsProps
 
         <div className="space-y-1 text-center">
           <p>
-            <span className="font-medium text-brand-500">Click to upload</span> or drag and drop
+            <span className="font-medium text-brand-500">Click to upload</span> or drag and drop a file
           </p>
           <p className="text-sm">(Up to {prettyBytes(maxSize)})</p>
         </div>