Docs: add Discord (community) and Bootstrap subreddit links (twbs#38873)

Co-authored-by: Rob Jones <[email protected]>
Co-authored-by: Mark Otto <[email protected]>
Co-authored-by: Julien Déramond <[email protected]>

Author: 4 people

README.md

@@ -177,7 +177,8 @@ Get updates on Bootstrap's development and chat with the project maintainers and
 
 - Follow [@getbootstrap on Twitter](https://twitter.com/getbootstrap).
 - Read and subscribe to [The Official Bootstrap Blog](https://blog.getbootstrap.com/).
-- Ask and explore [our GitHub Discussions](https://github.com/twbs/bootstrap/discussions).
+- Ask questions and explore [our GitHub Discussions](https://github.com/twbs/bootstrap/discussions).
+- Discuss, ask questions, and more on [the community Discord](https://discord.gg/bZUvakRU3M) or [Bootstrap subreddit](https://reddit.com/r/bootstrap).
 - Chat with fellow Bootstrappers in IRC. On the `irc.libera.chat` server, in the `#bootstrap` channel.
 - Implementation help may be found at Stack Overflow (tagged [`bootstrap-5`](https://stackoverflow.com/questions/tagged/bootstrap-5)).
 - Developers should use the keyword `bootstrap` on packages which modify or add to the functionality of Bootstrap when distributing through [npm](https://www.npmjs.com/browse/keyword/bootstrap) or similar delivery mechanisms for maximum discoverability.

site/content/docs/5.3/getting-started/introduction.md

@@ -146,7 +146,8 @@ For improved cross-browser rendering, we use [Reboot]({{< docsref "/content/rebo
 Stay up-to-date on the development of Bootstrap and reach out to the community with these helpful resources.
 
 - Read and subscribe to [The Official Bootstrap Blog]({{< param blog >}}).
-- Ask and explore [our GitHub Discussions](https://github.com/twbs/bootstrap/discussions).
+- Ask questions and explore [our GitHub Discussions](https://github.com/twbs/bootstrap/discussions).
+- Discuss, ask questions, and more on [the community Discord](https://discord.gg/bZUvakRU3M) or [Bootstrap subreddit](https://reddit.com/r/bootstrap).
 - Chat with fellow Bootstrappers in IRC. On the `irc.libera.chat` server, in the `#bootstrap` channel.
 - Implementation help may be found at Stack Overflow (tagged [`bootstrap-5`](https://stackoverflow.com/questions/tagged/bootstrap-5)).
 - Developers should use the keyword `bootstrap` on packages that modify or add to the functionality of Bootstrap when distributing through [npm](https://www.npmjs.com/search?q=keywords:bootstrap) or similar delivery mechanisms for maximum discoverability.