Add comments with reference links to scripts

[mkasberg]

When we use an argument parsing utility in our sample scripts (like getopts in bash), it would be good to link to the documentation of that library/method so someone who wants to modify the sample script can easily find a reference to read about how the method works and what it's capabilities are. Where possible, this should be a link to official documentation (instead of StackOverflow or a blog).

Example for bash: #81

[mkasberg]

Made progress in #84 and #87. Only language that could still use a link to the docs is perl.