Added C++ book "More C++ Idioms"

[chanibal]

What does this PR do?

Add resource(s): a new C++ book

For resources

Description

Describes a lot of functional patterns used in the C++ language.

Why is this valuable (or not)?

This book is quite unknown, but shouldn't be. It has great and quite unique mini-tutorials on how to use idioms that knowledge of is often taken for granted when someone mentions some solution.

How do we know it's really free?

Its on wikibooks, it has been authored there.

For book lists, is it a book? For course lists, is it a course? etc.

It is a book, it's self contained and while it contains stubs for expanding into new idioms, it has value in the form it currently is.

Checklist:

• Read our contributing guidelines
• Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction)

Follow-up

• Check the status of GitHub Actions and resolve any reported warnings!

[eshellman]

Thanks, and welcome to free-programming-books!