This isn't bad idea, but speaking in general there would be some heroes with more roles in same time, for example Thorin III. That hero is building/unit/hero supporter, tank and killer at same time. And for example you write all of this in description of citadel button of Thorin III. Would be that so useful to nobbie? I am giving just example, ofc there are many more heroes with different roles. Simply Gimly also DPS and Tank...
In general this could be also confusing if you take some of similar examples like those.
Personally I think it is best to read all descriptions of hero abilites and then decide how you want to play him and from gameplay mistakes to learn which is the best role for hero. It is the best way to learn possibilities of heroes and roles of same. Simply I really don't think that nobbie or someone who doesn't know how to play game will get some enlightenment with this information.
From my perspective, I think this is good idea but it will be also confusing for some heroes (because if their multi role), mainly if this is referring nobbie problems.
Kind regards