Fix incorrect filename in Makefile rule
As reported in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864612 , there is a copy and paste error in the Makefile rule for irk.html
The 17.0 major release is coming on May 16, 2024! This version brings many exciting improvements to GitLab, but also removes some deprecated features. We are introducing three breaking change windows during which we expect breaking changes to be deployed to GitLab.com. You can read more about it on our blogpost. The second breaking change window begins 2024-04-29 09:00 UTC and ends 2024-05-01 22:00 UTC.
As reported in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864612 , there is a copy and paste error in the Makefile rule for irk.html