fixed firewalld get_service_enabled
Merge pull request #4348 from maxamillion/fix_firewalld

fixed get_service_enabled call
An approach to explaining precedence more by convention.
Add check to make sure dopy is at least version 0.2.2 for digital_ocean module
Remove redundant section.
Add a note about registered variable lifetime.
Minor AWS doc cleanup
Slight cleanup to adhoc chapter.
Slight tweaks to config file chapter.
Slight tweaks to getting started.
Jinja2 link doc fixes
Misc docs fixes
Fix rst link format
Minor playbooks doc tweaks.
Slight accelerate mode page simplification.
Environment doc cleanup and showing another use case.
Explain error handling section better.
Misc rst tweaks
Update rst
Add append_privs parameter to MySQL user module.

This adds the privileges given to the existing list of privileges
instead of overwriting any existing ones.