The example code in the embedding documentation for calling C from Wren
incorrectly used `!isStatic` when checking for the static `add(_,_)` method
on the `Math` class. This caused the foreign method binding to respond to
non-static calls instead of static ones. Changed the condition to `isStatic`
so that `mathAdd` is correctly bound only when the method is invoked as a
static call.
- Delete the empty "Application Lifecycle" page (was just a TODO placeholder)
- Expand "Storing C Data" from stub to full documentation covering foreign classes, initialization, access, and finalization
- Add note that VM is not re-entrant; warn against calling wrenCall/wrenInterpret from foreign methods
- Fix broken cross-reference links (configuring-the-vm.html, wren.hpp include)
- Clarify slot API usage: remove confusing sentence about implicit return of receiver
- Fix grammar: "each VM them differently" → "each VM differently", "is only be called" → "is only called"
- Improve phrasing throughout for clarity and consistency
