slack channel link is wrong

[zoe-marie]

The link to the Slack channel on all pages is wrong.
It links to the old hardware lab channel and not the new makerspace channel

Old Link:
https://codeuniversity.slack.com/archives/C011CN2SMFY

New Link:
https://codeuniversity.slack.com/archives/C07RMQ361UZ

I sugest removing the link from all pages and only having it in the main README.md, so it can be changed easier in the future. If it ever changes again. 😄