Adds exception class, closes #2928

doc/Type/X/Dynamic/NotFound.pod6

@@ -0,0 +1,24 @@
+=begin pod :kind("Type") :subkind("class") :category("exception")
+
+=TITLE class X::Dynamic::NotFound
+
+=SUBTITLE Runtime error thrown when a dynamic variable does not exist
+
+    class X::Dynamic::NotFound is Exception {}
+
+This exception is raised when a dynamic variable that has not been declared
+is used.
+
+=for code :skip-test<Throws an exception>
+$*dynamic-not-found = 33;
+# OUTPUT: «Dynamic variable $*dynamic-not-found not found␤»
+
+=head1 Methods
+
+=head2 method name
+
+    method name(--> Str:D)
+
+Returns the name of the variable that has not been found.
+
+=end pod