Merge branch 'readme_leqi' into 'master'

Replace slack with discord [skipped]

See merge request data/monolith!2021

GitOrigin-RevId: 1f55222f15e659b451570973ee3c37df37b56ecf

README.md

@@ -11,9 +11,9 @@ Monolith is built on the top of TensorFlow and supports batch/real-time training
 
 ## Discussion Group
 
-### Join us at Slack
+### Join us at Discord
 
-https://join.slack.com/t/monolithusergroup/shared_invite/zt-1mewhxi5v-L7EPkRTaoONIbjtLCVALdw
+https://discord.gg/QYTDeKxGMX
 
 ## Quick start