Add GPL-3.0-or-later license to 'Matters Computational' book entry

[AkshayTiwari27]

What does this PR do?

Adds license information to the "Matters Computational: Ideas, Algorithms, Source Code" book entry in the C++ section.

For resources

Description:
The entry for "Matters Computational: Ideas, Algorithms, Source Code" has been updated to include its license information, which is GNU General Public License (GPL), version 3 or later.

Why is this valuable (or not)?

Adding license information improves transparency and helps users understand the usage rights associated with the book.

How do we know it's really free?

The license information was extracted from the preface section of the book, which explicitly states the terms under the GPL-3.0-or-later license.

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

Yes, this is a book.

Checklist:

• Read the contributing guidelines.
• Checked for duplicates using the search tool.
• Included author(s) and platform where appropriate.
• Put lists in alphabetical order with correct spacing.
• Added needed indications (PDF, access notes, under construction).
• Used an informative name for this pull request.

Follow-up

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

[eshellman]

at this time we are not adding license notation for GPL.

[AkshayTiwari27]

at this time we are not adding license notation for GPL.

Hi @eshellman,

Thank you for reviewing my pull request. I noticed that it was closed with the comment that license notation for GPL is not being added at this time. Could you please clarify if there are specific reasons for this decision? I’d like to understand better so that I can align my contributions with the project’s requirements.

If there’s a different way I could contribute or another area you’d like help with, please let me know!

Thank you for your time.

[eshellman]

have added comments in #11315. Sorry for the confusion. I thought it ha been specified there.