A place for Drupal coding best practices

Problem/Motivation

There are Drupal best practices that are not a coding standards but are best practice and can't be found if one is looking at the coding standards. One example is Creating custom assertion messages.

There are also related core issues.
#3560672: [policy, no patch] Decide if and where to adopt the #[NoDiscard] attribute
#3250827: [policy, no patch] Use declare(strict_types=1) in new code

Benefits

If we adopted this change, the Drupal Project would benefit by developers being able to easily find Drupal practices.

Three supporters required

1. https://www.drupal.org/u/{userid} (yyyy-mm-dd they added support)
2. https://www.drupal.org/u/{userid} (yyyy-mm-dd they added support)
3. https://www.drupal.org/u/{userid} (yyyy-mm-dd they added support)

Proposed changes

Some options

1. Add to existing Coding Standards docs
2. Add a new section in the Drupal documentation
3. ?

Remaining tasks

1. Create this issue in the Coding Standards queue, using the defined template
2. Add supporters
3. Create a Change Record
4. Review by the Coding Standards Committee
5. Coding Standards Committee takes action as required
6. Discussed at a Core Committee meeting, if it impacts Drupal Core
7. Final review by Coding Standards Committee
8. Documentation updates
   1. Commit the MR
   2. Publish change record
   3. Remove 'Needs documentation edits' tag
9. If applicable, create follow-up issues for PHPCS rules/sniffs changes

For a full explanation of these steps see the Coding Standards project page