Add myself to the ‘Developers’ list

Add myself (Karl Ove Hufthammer, aka ‘huftis’) to the developer page.

I’m not sure what it takes to be listed as a ‘developer’, but I’ve had a few (18) merge requests accepted so far.

Test Plan

Look at the ‘Help → About Krita → Authors’ page.

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.