[type.descriptions.general] Remove reference to undefined library concepts. (#1023)

Fixes #455.

Author: jensmaurer

source/lib-intro.tex

@@ -570,9 +570,7 @@
 \tcode{CopyConstructible}.
 Examples from~\ref{iterator.requirements} include:
 \tcode{InputIterator},
-\tcode{ForwardIterator},
-\tcode{Function},
-\tcode{Predicate}.}
+\tcode{ForwardIterator}.}
 These names are used in library Clauses
 to describe the types that
 may be supplied as arguments by a \Cpp program when instantiating template components from