Add title function and example of it. - #3

Nice, thanks for contributing!

Could you explain what you mean by "if PyDECREF, the show function doesn't work on Mac OS"?

Hi, lava. matplotlib-cpp is great. I'm looking for like this : )
The comment means that a figure doesn't show on Mac OS if the PyDECREF function is called at the end of "title" function.
Why do you call PyDECREF on the ends of other functhions?

All python objects are reference counted, so in your case you are leaking memory by creating three new objects that will never be removed.

It's a pretty small leak though, so if there is some bug on Mac OS that makes this necessary, I'm willing to just leave it. I don't have a Mac to verify it. Would be nice to know why the figure doesnt show, though.

OK I understand. yeah, I think the leak is not a problem on practical usage.

Thanks for merge 👍