Add the time complexities

[skyerguo]

• I have searched the issues of this repo and believe that this is not a duplicate.

Issue

I am wondering if you can add the calculation complexity (something like O(N^2)) in the documentation.
It would provide programmers with more information about how to pick an appropriate function.

[mgao97]

Got it! We will add it soon!

[tddschn]

@skyerguo @mgao97
I'm working on this task - a few quick questions

• There are so many functions and methods, where do I start?
• Should I just add the time complexities in the function docstrings?

[tddschn]

See https://github.com/tddschn/easygraph-function-time-complexities .

More are coming!