Add instructions for mining with s-nomp to Zebra book

[mpguerra]

Motivation

Detailed mining instructions point back to this zebra github repo instead of the Zebra book even though they are within the book directory.

Solution

Add the file to the contents on SUMMARY.md and link to its location in the book.

Review

Do we actually want to show this in the book or was it fine the way it was?

Reviewer Checklist

• Will the PR name make sense to users?
  • Does it need extra CHANGELOG info? (new features, breaking changes, large changes)
• Are the PR labels correct?
• Does the code do what the ticket and PR says?
  • Does it change concurrent code, unsafe code, or consensus rules?
• How do you know it works? Does it have tests?

Follow Up Work

[arya2]

Looks good!

[teor2345]

Do we actually want to show this in the book or was it fine the way it was?

I don't mind either way. s-nomp is not suitable for production mining, so we could leave it out of the index. But that also makes our docs less usable and hard to find.

[oxarbitrage]

Looks good, i made a suggestion to be more clear that the s-nomp guide is not production but feel free to ignore it.