Update Plugin Best Practices section on Avoid Naming Collisions to include namespaces as an option

[jonathanbossenger]

Issue Description

The Avoid Naming Collisions section of the Best Practices page in the Plugin developer handbook includes the options to use prefixes, and classes, but not namespaces, to avoid naming collisions.

We do have a section on using namespaces in our coding standards, so it makes sense to add this to our plugin developer handbook as well.

URL of the Page with the Issue

https://developer.wordpress.org/plugins/plugin-basics/best-practices/

Section of Page with the issue

The section Avoid Naming Collisions

Why is this a problem?

It doesn't include namespaces as a solution

Suggested Fix

Add a section on the use of namespaces as an option, after the prefix section. Include details on how to create good namespaces based on the WordPress coding standards

[github-actions]

Heads up @WordPress/docs-issues-coordinators, we have a new issue open. Time to use 'em labels.

[github-actions]

Heads up @theMikeD - the "plugins" label was applied to this issue.

[jonathanbossenger]

I am also offering to add the content for this section, and I will share a draft here for review in the next few days.

[jonathanbossenger]

Closing in favour of WordPress/developer-plugins-handbook#44