Add section for slack groups

[bganglia]

I have been scouring the web for bioinformatics slack groups, and wanted to share the ones I have found.

Would you be willing to add a section for slack groups? If not, I could also create my own list.

[Daniel E Cook]

Hello @bganglia - sure I can add a few. Or you can via pull request. Post the links here if you want me to add.

Thanks!

[bganglia]

@danielecook I can open a PR with mine, and would love to see yours too.

[Daniel E Cook]

@bganglia ping