Change "EA" to "EBA", fix a link, link "my EBA", and add periods at /handbook/ceo/.
This changes several instances of "EA" to "EBA", updates the "EBA handbook page" link to the new URL, links "my EBA" to https://about.gitlab.com/handbook/eba/#executive-business-administrator-team, and adds a few missing periods at https://about.gitlab.com/handbook/ceo/.
Edited by Brian Sexton