Plural in headings, update intro

Author: tkoeppe

source/lib-intro.tex

@@ -1574,8 +1574,8 @@
 \rSec3[utility.requirements.general]{General}
 
 \pnum
-\ref{utility.arg.requirements}
-describes requirements on types and expressions used to instantiate templates
+Subclauses \ref{utility.arg.requirements}--\ref{utility.req.cpp17.destructible}
+describe requirements on types and expressions used to instantiate templates
 defined in the \Cpp{} standard library.
 \ref{swappable.requirements} describes the requirements on swappable types and
 swappable expressions.
@@ -1625,7 +1625,7 @@
 \tcode{T()} shall be a well-defined expression\iref{dcl.init} if one of those
 signatures is called using the default argument\iref{dcl.fct.default}.
 
-\rSec3[utility.req.cpp17.equalitycomparable]{\oldconcept{EqualityComparable} requirement}
+\rSec3[utility.req.cpp17.equalitycomparable]{\oldconcept{EqualityComparable} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{EqualityComparable} requirement
@@ -1654,7 +1654,7 @@
 \end{itemize}
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.lessthancomparable]{\oldconcept{LessThanComparable} requirement}
+\rSec3[utility.req.cpp17.lessthancomparable]{\oldconcept{LessThanComparable} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{LessThanComparable} requirement
@@ -1674,7 +1674,7 @@
 \tcode{<} is a strict weak ordering relation\iref{alg.sorting}.
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.defaultconstructible]{\oldconcept{DefaultConstructible} requirement}
+\rSec3[utility.req.cpp17.defaultconstructible]{\oldconcept{DefaultConstructible} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{DefaultConstructible} requirement
@@ -1711,7 +1711,7 @@
 A value-initialized or aggregate-initialized object of type \tcode{T}.
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.moveconstructible]{\oldconcept{MoveConstructible} requirement}
+\rSec3[utility.req.cpp17.moveconstructible]{\oldconcept{MoveConstructible} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{MoveConstructible} requirement
@@ -1759,7 +1759,7 @@
 \end{note}
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.copyconstructible]{\oldconcept{CopyConstructible} requirement}
+\rSec3[utility.req.cpp17.copyconstructible]{\oldconcept{CopyConstructible} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{CopyConstructible} requirement
@@ -1785,7 +1785,7 @@
 The value of \tcode{v} is unchanged and is equivalent to \tcode{T(v)}.
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.moveassignable]{\oldconcept{MoveAssignable} requirement}
+\rSec3[utility.req.cpp17.moveassignable]{\oldconcept{MoveAssignable} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{MoveAssignable} requirement
@@ -1822,7 +1822,7 @@
 \end{note}
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.copyassignable]{\oldconcept{CopyAssignable} requirement}
+\rSec3[utility.req.cpp17.copyassignable]{\oldconcept{CopyAssignable} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{CopyAssignable} requirement
@@ -1846,7 +1846,7 @@
 \tcode{t}.
 \end{itemdescr}
 
-\rSec3[utility.req.cpp17.destructible]{\oldconcept{Destructible} requirement}
+\rSec3[utility.req.cpp17.destructible]{\oldconcept{Destructible} requirements}
 
 \pnum
 A type \tcode{T} meets the \oldconcept{Destructible} requirement