[BUG] Machine inventory guide not visible in the academy

[darigovresearch]

Currently you need to know about the machine inventory in order to be able to find the link to the guide & the link to the site. Would be helpful to have this linked in the academy side panel to make it more discoverable to users who don't watch the monthly news updates actively.

Guide in question - https://github.com/ONEARMY/academy/blob/master/docs/guides/machine-inventory.md

Suggested location from the file

Suggested location in academy