Add aria labels to icons that link to help_page_path

While working on !41970 (merged) with @jeldergl, we noticed a few improvements that can be made to some of the links that use icons and link to help_page_path (docs pages).

To be clear, the icons that use the following pattern should be updated:

= link_to sprite_icon('question-o'), help_page_path('user/permissions')

There are also instructions on how to include them in doc/development/documentation/index.md which should be updated as well.

The improvements are:

• Consider adding an aria-label to the SVG. This should help us have better accessibility. For example, we can have a label like Go to X help page to learn more.
• Consider NOT opening the help page in a new tab. This requires users to switch context and prevents them from using the back button.