Ensure all Last Updated dates are correct

[mayarichman]

Re: Current Digital Security Resources

When developing security resources, we should aim to…
Be clear about when the guide has been updated (e.g., the EFF notes the dates its Surveillance Self-Defense modules are updated), and if possible, what changed. For example, Tactical Tech often uses revision histories, while Internews makes some resources available on GitHub.
Be transparent if the information is expected to get out of date. There are many ways to do that. (e.g., matt mitchell uses “best by” dates.)
Be clear about the level of commitment to updating the information. In some cases, it’s fairly clear that the document will not be updated (e.g., in large news publications), but often our commitment to keeping guides updated is not clear to the unfamiliar reader.