ServerCompatBanner [nfc]: Add TODO to link to more user-friendly doc

Author: chrisbobbe

src/common/ServerCompatBanner.js

@@ -96,6 +96,8 @@ export default function ServerCompatBanner(props: Props): Node {
           label: 'Learn more',
           onPress: () => {
             openLinkWithUserPreference(
+              // TODO: Instead, link to new Help Center doc once we have it:
+              //   https://github.com/zulip/zulip/issues/23842
               'https://zulip.readthedocs.io/en/stable/overview/release-lifecycle.html#compatibility-and-upgrading',
               settings,
             );