People tagged by keywords to choose from a pool of reviewers via keyword e.g. 'backend'

I would like to have people in bitbucket be able to tag themselves with keywords like 'frontend' and/or 'backend', etc., so that when people want to assign their pull request they can choose e.g. 'backend' and get a drop-down of people who are tagged as such. 

Motivation is to get an easy overview of reviewers available so not always the same are put on a PR.