Consistency tweaks: Add <code> around executable name

Spotted by Siebrand
https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Math_notexvccheck/en

While I am on it: Always use https for mediawiki.org

Change-Id: I227540a4cc5529c9db44dbbfda617f9b81db7274
Merge "Consistency tweaks: Add <code> around executable name"