add and update various titles & meta descriptions
added robots option to head
no-indexed deprecated documentation

this documentation isn't super handy for users and may affect our
crawl budget, it's additionally near dublicate of the non-deprecated
stuff

users still have access to these docs, they just will not be able to
google for it. however, other users may not get confused by having these
in the results
added inherent microdata
added language to github links

done for microdata’s sake
microdata videos
Merge pull request #419 from sendgrid/spot-seo

seo changes