Unnecessary `<meta http-equiv>` tags

[wong-justin]

I was reading through the example HTML file and saw some <meta http-equiv> tags:

https://github.com/robinmoisson/staticrypt/blob/27a564ac611e01f0b3589e56eb36df1f8b54381d/example/encrypted/example.html#L10-L13

I'm pretty sure these cache control directives are ignored by browsers, so they should probably be removed.

However, it would be good to keep the "do not cache this page" comment, or even to elaborate in the comment and in the documentation, recommending developers to configure their server's HTTP headers to not cache these pages.

There's a good blog post about <meta http-equiv> tags, and you can also check the MDN reference or the HTML spec on the topic.