readme: add link to GUI releases
readme: add link to GUI releases

beancount/fava,yagebu/fava,aumayr/beancount-web,aumayr/beancount-web,beancount/fava,aumayr/beancount-web,yagebu/fava,yagebu/fava,beancount/fava,yagebu/fava,aumayr/beancount-web,beancount/fava,beancount/fava,yagebu/fava