Update join beam doc (#34284)

* Update Join me page for slack channel

* fix formatting issue

Author: rakeshcusat

website/www/site/content/en/contribute/attributes.md

@@ -50,7 +50,7 @@ In particular, a Beam committer strives to:
 - They can be trusted to decide when code is ready for release, or when to ask someone else to make the judgment
 - They can be trusted to decide when to merge code (if a code contributor) or when to ask someone else to make the judgment
 
-[To learn more see the ASF documentation.]((https://www.apache.org/dev/committers.html#committer-responsibilities)
+[To learn more see the ASF documentation.](https://www.apache.org/dev/committers.html#committer-responsibilities)
 
 {{< figure src="/images/community/beam-logo-icon.svg" >}}
 

website/www/site/data/en/join_beam.yaml

@@ -12,7 +12,7 @@
 
 - list:
     - { title: Mailing Lists, description: 'Join the official Apache Beam user and developer mailing lists. Learn how <a href="/community/contact-us/">here</a>' }
-    - { title: Slack Channel, description: 'For real-time communication, join us on the <a target="_blank" href="https://app.slack.com/client/T4S1WH2J3/C9H0YNP3P">#beam</a> channel in the ASF workspace.' }
+    - { title: Slack Channel, description: 'For real-time communication, join us on the <a target="_blank" href="https://app.slack.com/client/T4S1WH2J3/C9H0YNP3P">#beam</a> channel in the ASF workspace. If you are not part of ASF workspace yet then ask in the <a href="/community/contact-us/">dev mailing list</a> for an invite.' }
     - { title: Twitter account, description: 'Follow <a target="_blank" href="https://twitter.com/apachebeam?lang=en">@ApacheBeam</a> on Twitter for the most recent news on the project and community!' }
     - { title: YouTube channel, description: 'Follow our <a target="_blank" href="https://www.youtube.com/channel/UChNnb_YO_7B0HlW6FhAXZZQ">YouTube channel</a> for the latest training and use cases.' }
     - { title: StackOverflow, description: 'Ask your Beam questions in StackOverflow using the <a target="_blank" href="https://stackoverflow.com/questions/tagged/apache-beam">apache-beam tag</a>.' }