It has fallen out of date and needs updating to reflect the current codebase:

• Remove mentions of UserException and MsgAssertionException since they were deleted years ago
• Mention ExceptionFor<> and how it supports both codes and categories
• (perhaps controversial) Move dassert out of the "deprecated" section since it is still used and is the recommended way to achieve debug-only asserts. We should add an admonition that it is a sharp tool that should only be used where it provides enough benefit to be worth the risk.
• We should stop saying that anything is "operation fatal" unless it is actually supposed to be illegal to catch and handle the error within the context of a successful operation
• Consider renaming it to "Error Handling" since it covers more than just exceptions
• Give it a general look over to see if there are any other changes that are needed