Update README to add notes about what this repo contains

[pavithraes]

• Logos
• Meeting notes
• Governance documents

We can also highlight the CoC and license in the readme.

[BhaswatiRoy]

Hello @pavithraes
I can work on the improvement of the README of the repository. It would be great if I could be assigned.

[bryevdv]

Hi @BhaswatiRoy since Bokeh is a volunteer effort, we don't really utilize active assignments (some folks like to self-assign for their own sake) Feel free to go ahead and submit a Pull Request!