[res.on.exception.handling] use grammarterm instead of informal term and add ref

Author: Eisenwave

source/lib-intro.tex

@@ -3795,7 +3795,7 @@
 can report a failure by throwing an exception of a type
 described in its \throws paragraph,
 or of a type derived from a type named in the \throws paragraph
-that would be caught by an exception handler for the base type.
+that would be caught by a \grammarterm{handler}\iref{except.handle} for the base type.
 
 \pnum
 Functions from the C standard library shall not throw exceptions%