The Vote-to-Close dialog contains a number of links to the #close section of the FAQ, but that part of the FAQ is really just the same text as in the dialog box, plus a statement of what closure is. It appears to be relevant to the Closee but not the Closer.
There is a link in the existing FAQ to the useful How to Ask page, but its in this context:
See How to Ask for guidance on editing your question to improve it.
In most cases the Closer will not be the OP.
The FAQ links in the Vote-to-Close dialog should be relevant to the Closer - informing their voting process.
So, my suggestion is to write (probably by collating some meta posts) a FAQ section specifically aimed at Closers. This should have expanded notes for each close reason, and ideally, a link to the (a?) FAQ section on editing-to-improve posts if they might be salvaged and reopened.
I'm happy to try to draft something, but would welcome suggestions in respect of this.