* Added "Determining which type of environment variables to use"
* Moved into reusable, added to various locations
* Added some small edits
* Some rewording
* Revised example
* Removed reusable reference from one location
* Update context-and-expression-syntax-for-github-actions.md
* Fixed merge conflict
* Update environment-variables.md
* Apply suggestions from code review
Co-authored-by: Sarah Edwards <skedwards88@github.com>
* Update using-context-or-environment-variables.md
* Clarified locations of context variables
* Clarified the distinction between contexts and default environment variables
* Moved section up
* Clarified that _most_ contexts can be used anywhere
Co-authored-by: Sarah Edwards <skedwards88@github.com>
