Caveat to the above post – even though the link and icon will look correct the hover over text will be incorrect (e.g. Follow us Us on Dribble instead of Follow Us on Instagram). Probably a way to updated this in the CSS but for me it has not been worth the effort. May or may not be a big deal to others.
No need to mess with code (imo). In the Tesseract theme you will notice that all of the social media choices are configured with just a URL link and uploaded icon of your choice. While Instagram and Reddit are not in the configuration list you could simply pick one of the other options you are not using (e.g. Dribble or Vimeo) and simply upload the Instagram logo and link to it. While this may not be ideal as you will have to remember your mapping choice it will provide you a workaround.
