make metadata more robust (description)

[leanne-fan]

we want to give users flexibility to add what that way but also maintain some rigidity for magic of yaml!

metadata needs to be more robust, right now in attempt to re-create how it was, the yaml for the workshop is a "bear"

change "excerpt" to description "excerpt" is used a lot in the yaml file incorrectly *make friendly colors on the highlight!!

We could either get rid of all the magic What requires magic

[szweibel]

Please split this into separate issues @leanne-fan

[szweibel]

And after splitting them please close the original @leanne-fan (I'll do this one)