🚀 feat: Upgrade Makefile for better compability with manpath

[FelipeFTN]

Hello folks!

I'm just sending this changes to fix a little problem I had when building the project from source.
Looks like we were using hard-coded path values for man1... 🤔
What happens is, in some machines the man paths may vary (in my case, for example, it is located at /usr/share/man).

So I added some logic to try to dynamically find the man1 file in our system 🔍
Now it looks just great, and it's no longer breaking in my system when building from source! 🎉 I hope that works in your computer as well haha

So, what I'm doing is getting the man's path variable with the command manpath. This command will generate a simple PATH string like this: /usr/local/man:/usr/local/share/man:/usr/share/man. So I split it by : and try to find the correct directory inside each path. Then, set the variable, and do all the stuff...

That's it! 🚀

[tycho-kirchner]

Thanks for that. I guess I'll merge this, but before, I'll briefly look how this is done in other projects. As the priority is quite low, I'll probably leave it here until end of July, but it's not forgotten (: