chore: implement validation for accepting 'http://' and 'https://' url in link modal (#3147)

web/components/core/modals/link-modal.tsx

@@ -118,6 +118,7 @@ export const LinkModal: FC<Props> = (props) => {
                                 ref={ref}
                                 hasError={Boolean(errors.url)}
                                 placeholder="https://..."
+                                pattern="^(https?://).*"
                                 className="w-full"
                               />
                             )}