Feed API helper page is broken on emoncms.org & Emoncms V9.7

**Issue**
When logged into emoncms.org clicking on 'Feed API Helper' links to this page https://emoncms.org/api which results in a blank screen. 

On local emoncms (V9.7)  error message `URI not acceptable. No controller 'api'. (/)` is shown 

**Solution***

The correct URL should be  https://emoncms.org/feed/api

Discussion: https://community.openenergymonitor.org/t/feed-api-not-working/767
