add stock_messages page and add it to the messages_overview
added doccumentation for fosdick
Fixed order_update message key value
Updating Push guide
Added details on endpoint.json and registering custom endpoints
Reword Notification vs. Message
Typo fixes
s/integrator/hub
Zendesk Endpoint documentation
Fixes to url and password params explanation - zendesk documentation
Fixed outgoing message description on the zendesk integration documentation
use json to format
headers
Add metadata description for most API guides