After I choose an extension and version, the generated page says
"The tar archive should be extracted into your extensions directory. For example, on a unix-like OS:"
Avoid passive voice when conversing with the reader, especially when it sounds like it's saying what the browser will normally do. Also capitalize Unix, so:
"You should extract the tar archive's contents into the <tt>extension</tt> directory of your MediaWiki installation. For example, on a Unix-like OS:
"It may be used for immediate download to a server, but please do not bookmark it, since the contents will not be updated..."
"You can use this link to download the extension on any computer, but please do not bookmark it, since its contents will not be updated..."