A few stores allow you to add a bio to your artists' pages.
If you wish to do so, please proceed as folows :
Adding a bio to your artist's Spotify page must be done through Spotify for Artists.
Please note that only the artists themselves (or eventually their management) may have access to this interface.
Also see the article : Spotify for artists
Send your bio along with your artist's Apple ID to firstname.lastname@example.org
Send your artist's bio to your Labels and Artists Support team along with the link to artist's page on Deezer.