To me, "obsolete" manes "no longer appliable" - basically, "the information in this page doesn't apply any more".
Some (made up) examples:
- "Can Phorge run on PHP 7.0?" (The answer is no, because of a specific bug in 7.0, which was EOL a long time ago)
- "I have this problem in the Chatbot app" (We've deleted the chatbot app)