Update readme

[juliandavidmr]

Regarding the documentation of this fork. I think the installation command shown in the README should be changed, as npm install jison -g appears but should be npm install jison-gho -g.
I have seen that this fork contains many improvements over the original project, but I am convinced that this fork is the one that everyone should install.

I created this issue because at first I didn't know how to install this fork, so I took some time to find out what the installation command was. He always installed the original because it was the one that appeared in the documentation of this fork.

Thanks.

[GerHobbelt]

Good catch! 👍

[GerHobbelt]

fixed in commit SHA-1: 9bb9f97

[GerHobbelt]

Should be visible now (as github shows master branch) while this is effective in the npm archive once 0.6.5 comes out.