How to find specific files in the github

I've been poking around in the github directory trying to understand linuxcnc a bit better, but the files keep referring to other files which I just. Can't. Find. For example one .ini file I've been looking at to figure out my own .ini file refers to "5axis.var", but I can't find where it is and there's just so many files. It took me several minutes to find "basic_sim.tcl" and that one had the hint of "LIB:" in front of it in the file I was looking at. I can't find a search function on github, is there some kind of directory tree document or something that I could ctrl+f through to find where specific files are or do I just need to poke around until I find it?

Oh. Thank you. I found it in the config file of a sim I'd already loaded.

Still, there are other files I've only been able to find after a lot of searching; since you didn't mention an easy-to-search document, would it be safe to assume there isn't one...? I don't mind searching around if I have to, but would like to make sure I'm not making it harder on myself than it has to be!

Git is a source repository. Some files are created as part of the make process from that source code.
You would probably be better off compiling a run in place version of linuxcnc and using grep to find files as everything will be under the linuxcnc-dev folder somewhere.