The Build page covers how to gear including: Major & Minor Essences, Azerite Traits, Azerite Pieces & Trinkets for each spec as pertaining to Mythic+. Use the links below to navigate to a certain spec, or use the drop down menu on the main navigation bar.
At the moment, the only spec the website covers is Beast Mastery. Marksmanship and Survival are greyed out and do not link anywhere. Once the site is updated for each spec, the links will become normal.