Adds explanatory prose related to delegate. (#246)

This resolves the last three so far unaddressed `todo::` sections:
- Add prose explaining try-delegate's jump.
- Adds prose and intuition for delegating exception handlers.
  + Also a minor modification to the prose of catching exception handlers, that somewhat reduces calling the administrative instruction by its identifier (CAUGHTadm) in the prose.

Co-authored-by: Andreas Rossberg <[email protected]>

Author: ioannad

document/core/syntax/instructions.rst

@@ -694,8 +694,8 @@ In case of |BLOCK| or |IF| it is a *forward jump*,
 resuming execution after the matching |END|.
 In case of |LOOP| it is a *backward jump* to the beginning of the loop.
 
-.. todo::
-   Add prose for try-delegate's jump.
+When |TRY|--|DELEGATE| handles an exception, it also behaves similar to a forward jump,
+effectively rethrowing the caught exception right before the matching |END|.
 
 .. note::
    This enforces *structured control flow*.