IIP-0001: Add description of the editor role in the IIP process

[MitchellCash]

This modification to IIP-0001 defines the role of an editor (an editor is someone who has the ability to make changes to the IIP repository).

I want to bring specific attention to this role:

IIP editors may also, at their option, unilaterally make and merge strictly-editorial changes to IIPs, such as correcting misspellings, fixing broken links, etc.

To improve the turnaround and workflow of simple editorial changes, this allows Editors to merge changes that correct minor mistakes in an IIP without changing anything fundamental.

[MitchellCash]

@adammatlack & @mdpfeiffer as the original authors of this IIP could you please review this change and offer your feedback?

[mdpfeiffer]

I like it. Let's add that.