😍 Update "what is OSB" copy to better reflect current conference

[reidab]

A lot of our website copy and the things we use to make a first impression of the conference have remained unchanged for many years. The conference has evolved over time and I'd like us to make sure our public face reflects this.

Things to review:

• http://opensourcebridge.org sidebar and main body
• http://opensourcebridge.org/about/
• ???