Change Details

https://github.com/wikimedia/mediawiki/blob/master/docs/design.txt is old and not very useful, but is probably frequently skimmed by new developers. Let's make it useful. https://www.mediawiki.org/wiki/Architecture_guidelines is what we //should// want people to read. That document should be taken with the same level of seriousness that https://www.mediawiki.org/wiki/Security_for_developers gets. Let's actually make a piece of it part of our source tree, and point to https://www.mediawiki.org/wiki/Architecture_guidelines from docs/design.txt