Update README.md

[jpfairbanks]

add install instructions

[rohitvarkey]

Now that JuliaLang/METADATA.jl#11174 is merged,Pkg.add should work.

[jpfairbanks]

I updated it, I think there might be something wrong with the foralledges function. Is the neighbor field being initialized correctly? See the example in this commit.

[rohitvarkey]

The edge from foralledges has the first 2 bits set to directions. edgeparse on the edge will give the correct neighbor value. This example in the docs shows how to use it.

Maybe I should roll this into foralledges to prevent the confusion?

[jpfairbanks]

A docs change will be sufficient. I totally forgot about this step when making the example.