fix catch clause grammar typos

Author: owenv

proposals/NNNN-multi-pattern-and-conditionally-compiled-catches.md

@@ -99,12 +99,12 @@ catch-clause -> 'catch' catch-item-list? code-block |
                 conditional-catch-clause
 
 catch-item-list -> catch-item |
-                   catch-item ',' case-item-list
+                   catch-item ',' catch-item-list
 
 catch-item -> pattern where-clause? |
               where-clause
 
-conditional-catch-clause -> catch-if-directive-clause catch-elseif-directive-clauses? switch-else-directive-clause? endif-directive
+conditional-catch-clause -> catch-if-directive-clause catch-elseif-directive-clauses? catch-else-directive-clause? endif-directive
 
 catch-if-directive-clause -> if-directive compilation-condition catch-clauses?