feat: add check mk

[matchett808-gh]

[ x] I'm submitting a template app

• [ x] I have added a .ini file to DashMachine with the same name used for [App Name] in the .ini file (e.g. 'App Name.ini')
• [ x] My .ini has the exact format as the others in the folder, only changing the name, icon location, and description.
• [ x] I used the official description and name for the app, found on their repository/website.
• [ x] I chose an icon (.png file) sized over 64px, with a transparent background, square aspect ratio, preferably the icon only version (not icon w/ text) of the app's icon.
• [ x] I understand that the icon will be resized to 64px x 64px and have verified that it looks good at that size.
• [x ] I have added the icon to static/images/apps with the correct name matching what's in the .ini.
• [x ] I tested it to make sure it looks good in the interface

The icon isn't exactly square but looks good as is

So that I can claim hacktoberfest credits for this - can you mark this PR as < hacktoberfest-accepted > (as a label - details of the why can be found here: https://hacktoberfest.digitalocean.com/details#maintainers)