Adding character cap on mobile discord for the about me.

Basically just the title. I had a problem earlier where I had no idea my about me was too long, so I submitted a support ticket about it and figured it out a bit later before I realized they had responded. This problem could have been avoided had I been informed by the app itself that my about me that I was wanting to switch it to was too long. This was an even bigger problem because I was used to discord informing me that on the computer app.