Added the Metapatterns website

[denyspoltorak]

What does this PR do?

Add resource(s)

For resources

Description

Architectural Metapatterns website

Why is this valuable (or not)?

It can be read online

How do we know it's really free?

It's public

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

It's a web version of a book

Checklist:

• [x ] Read our contributing guidelines.
• [x ] Search for duplicates.
• [x ] Include author(s) and platform where appropriate.
• [x ] Put lists in alphabetical order, correct spacing.
• [x ] Add needed indications (PDF, access notes, under construction).
• [x ] Used an informative name for this pull request.

Follow-up

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

[github-actions]

Linter failed, fix the error(s):

free-programming-books/books/free-programming-books-subjects.md
893:217-893:251  warning  Remove trailing slash (https://metapatterns.io)  no-url-trailing-slash  remark-lint