Fix references to new Clause 1, Clause 2, and Clause 3 to include the word "Clause".

Author: zygoloid

source/intro.tex

@@ -325,7 +325,7 @@
 If a program contains no violations of the rules in this
 International Standard, a conforming implementation shall,
 within its resource limits, accept and correctly execute\footnote{``Correct execution'' can include undefined behavior, depending on
-the data being processed; see~\ref{intro.defs} and~\ref{intro.execution}.}
+the data being processed; see Clause~\ref{intro.defs} and~\ref{intro.execution}.}
 that program.
 \item
 \indextext{message!diagnostic}%

source/lib-intro.tex

@@ -1111,7 +1111,7 @@
 Except as noted in Clauses~\ref{library} through~\ref{\lastlibchapter}
 and Annex~\ref{depr}, the contents of each header \tcode{c\placeholder{name}} is
 the same as that of the corresponding header \tcode{\placeholder{name}.h} as
-specified in the C standard library~(\ref{intro.refs}).
+specified in the C standard library (Clause~\ref{intro.refs}).
 In the \Cpp standard library, however, the
 declarations (except for names which are defined as macros in C) are within
 namespace scope~(\ref{basic.scope.namespace}) of the namespace \tcode{std}.

source/templates.tex

@@ -2621,7 +2621,7 @@
 
 \pnum
 The signature of a function template
-is defined in~\ref{intro.defs}.
+is defined in Clause~\ref{intro.defs}.
 The names of the template parameters are significant only for establishing
 the relationship between the template parameters and the rest of the
 signature.