Add details on PubMatic adSlot now being optional as Prebid v2.13.0 (#1301)
Add details on PubMatic adSlot now being optional as Prebid v2.13.0 (#1301)

* Add details on PubMatic adSlot being optional as of Prebid.js
v2.13.0

* Fix typos in prior commit

* Another typo

prebid/prebid.github.io,prebid/prebid.github.io,prebid/prebid.github.io,sonobi/prebid.github.io,sonobi/prebid.github.io,sonobi/prebid.github.io