DOCSP-34891: Add admonition to mention users must catch errors raised…

… by withTransaction() callback

source/fundamentals/transactions.txt

@@ -177,6 +177,11 @@ if a callback you pass to the ``withTransaction()`` method returns the
 document ``{ hello: "world" }``, then the ``withTransaction()`` method
 also returns that document.
 
+.. important::
+
+   To avoid infinite looping errors, ensure that the callback you pass to
+   the ``withTransaction()`` method catches any errors that it raises.
+
 When you use the Convenient Transaction API, you
 can propagate return values from the callback as the return values of
 the ``withTransaction()`` and ``withSession()`` methods to