Project conventions: documentation

[ttarczynski]

One of our conventions is not yet documented and not enforced with bin/check* scripts.
It is:

• There should be comments explaining and linking to documentation
• Please compare: google/google_compute_instance/simple/main.tf

The comments that we want to have in all examples:

• # Summary: – 1-line summary of what this example does
• # Documentation: – add link to documentation before each block (terraform, provider, variable, resource, etc.)
• # Explanation: – add only where some extra explanation is needed

TODO:

• add this convention to README
• add a bin/check_docs.sh script to enforce documentation conventions #183