Update index.php

Re-arranging some of the APIs and flagging SSO as depreciated.
Update index.php

Depreciating SSO
Update nav.php

Depreciating SSO
Update index.php

adding emphasis on items API.
Update nav.php
Update index.php

Removing "API" from the title.
Copy change for items api landing page
Fixed typo
[CHANGE] Removed 'slide' transition from Assess API demos and activity builder.
Merge from lndash