Remove readme text from meta file, convert synopsis to Markdown
Replace reStructuredText README with Markdown README
fix: Add a syntax checker for postfix

This change will run a syntax check on the postfix
configuration.
You can test it by removing your fqdn from /etc/hosts
after this, rerunning this recipe will fail, because
the postfix check will fail.
Merge pull request #7 from do3cc/postfix_check

fix: Add a syntax checker for postfix