Feature Request: Edit description etc on linked card

## Issue

**Server Setup Information**:

* Wekan version: 1.69.0
* Deployment Method(snap/docker/sandstorm/mongodb bundle/source): snap

**Problem description**:
Can't save description on linked card.

![output](https://user-images.githubusercontent.com/98204/48273495-5e3f1600-e441-11e8-9ab0-ba94734e54e2.gif)
(not in gif - I clicked Save)