remobe slack and change forum to community

[shrutika2110]

---

This change is 

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[joshua-goldstein]

@MichelDiz Closing because all changes in wiki.