Probably, you didn't notice before, but you can't add an hastag to your instagram profile's bio before. Now, you can. In a new Instagram blog post, while editing your profile, you can add an hastag (#) or "@" to your profile's bio. This would help you link directly to post or profile related to the tag.

With this new feature, you can link your instagram profile to your interests, and also to you having mutiple account, you can link directly to the other accounts. This upgrade certainly comes in handy. On my account I can decide to add at #BBNaija and @TobiBakre. Choose your choice.

One step to follow actually is that you have to update your Instagram app (If you are not using the latest one), as this feature is only available on the latest instagram app version

Source:
http://www.blackpenng.com/2018/03/instagram-rolls-out-new-update-to-bio.html?m=1