Add smart-quote-{disable,enable} scripts

[unixorn]

Description

Add helper scripts to toggle smart-quote substitution

Type of changes

• Add/update a helper script
• A link to an external resource like a blog post or video
• Text change (fix typos, update formatting)

Copyright Assignment

• This document is covered by the Apache License, and I agree to contribute this PR under the terms of that license.

Checklist:

• All new and existing tests pass.
• Any scripts added use #!/usr/bin/env interpreter instead of direct paths (#!/bin/sh is an ok exception)
• Scripts are marked executable
• I have added a credit line to README.md for the script
• If there was no author credit in a script added in this PR, I have added one.
• I have confirmed that the link(s) in my PR are valid.
• I have read the CONTRIBUTING document.

[codeclimate]

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