Pick a license for content and verify material

[dcwalk]

If these resources are intended to be reused I suggest we add a license (CC BY-SA 4.0 International being my go to for this type of material). Further, we should attribute the images used.

[benhylau]

I am ok with license change. Yea I should do a better job attributing images. I did the unique ones, but not the ones that are generic (e.g. the Raspberry Pi). Can we put the attribution in the notes and not the actual slide to save screen real estate?

[dcwalk]

Can definitely attribute in notes (or in readme, I don't even know if it has to be inline)!