mingw: sanitize line breaks in paragraphs
    
    As a result of automated conversion from previous formats, the paragraph
    text is mostly unbroken long lines, but there are also some arbitrary
    line breaks present. Long lines lead to very unfriendly patch diffs,
    both for command line tools, and also online review tools like Pagure.
    Thus this commit breaks all paragraphs at 79 characters.
    
    Tables and formatted examples are left untouched, since their content is
    easier to review if it is allowed to extend to its natural formatted width.
    
    Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>