Fixing link to GIF in README
Fixing link to GIF in README

I accidentally linked it to the branch in the first PR :p
mattermost/desktop,yuya-oc/electron-mattermost,jnugh/desktop,mattermost/desktop,mattermost/desktop,yuya-oc/electron-mattermost,jnugh/desktop,yuya-oc/electron-mattermost,mattermost/desktop,yuya-oc/desktop,St-Ex/desktop,yuya-oc/desktop,mattermost/desktop,St-Ex/desktop,yuya-oc/desktop,jnugh/desktop,St-Ex/desktop