Fixup merge/reword "two kinds of implementations" wording from [library] into [intro.compliance]

Author: eisenwave

source/intro.tex

@@ -833,18 +833,17 @@
 \indextext{conformance requirements!library|)}
 
 \pnum
-An implementation is either a
-\defnadj{hosted}{implementation} or a
-\defnadj{freestanding}{implementation}.
-A freestanding
-implementation is one in which execution may take place without the benefit of
-an operating system.
-A hosted implementation
-supports all the facilities described in this document, while
-a freestanding implementation
+A \defnadj{freestanding}{implementation}
+is one in which execution may take place
+without the benefit of an operating system.
+A \defnadj{hosted}{implementation}
+supports all the facilities described in this document,
+while a freestanding implementation
 supports the entire \Cpp{} language
 described in \ref{lex} through \ref{\lastcorechapter} and
 the subset of the library facilities described in \ref{compliance}.
+It is \impldef{whether the implementation is hosted or freestanding}
+whether the implementation is hosted or freestanding.
 
 \pnum
 It is

source/lib-intro.tex

@@ -1579,13 +1579,8 @@
 \indextext{implementation!freestanding|(}%
 
 \pnum
-Two kinds of implementations are defined:
-\indextext{implementation!hosted}%
-hosted and freestanding\iref{intro.compliance};
-the kind of the implementation is
-\impldef{whether the implementation is hosted or freestanding}.
-For a hosted implementation, this document
-describes the set of available headers.
+For a hosted implementation,
+this document describes the set of available headers.
 
 \pnum
 A freestanding implementation has an