Create standard location for "announcements" to be read at the top of every show

We should have a central markdown file (this repo is probably fine for it) that contains the script that should be read at the beginning of each show. This would always include the CNCF disclaimer, but we could insert channel announcements in it (example: "we will be taking next week off", etc)

all hosts should always read directly from this, to ensure that it's always correct.

I will take ownership of creating this per @danpopSD lol