[projected, alg.req.ind.{move, copy}, range.as.rvalue.overview] Article "an", not "a" (#6186)

The subsequent identifier is naturally pronounced with a leading vowel.

Author: morinmorin

source/algorithms.tex

@@ -436,7 +436,7 @@
 The behavior of a program is undefined if
 it invokes a vectorization-unsafe standard library function
 from user code
-called from a \tcode{execution::unsequenced_policy} algorithm.
+called from an \tcode{execution::unsequenced_policy} algorithm.
 \begin{note}
 Because \tcode{execution::unsequenced_policy} allows
 the execution of element access functions
@@ -523,7 +523,7 @@
 The behavior of a program is undefined if
 it invokes a vectorization-unsafe standard library function
 from user code
-called from a \tcode{execution::parallel_unsequenced_policy} algorithm.
+called from an \tcode{execution::parallel_unsequenced_policy} algorithm.
 \begin{note}
 Because \tcode{execution::parallel_unsequenced_policy} allows
 the execution of element access functions

source/iterators.tex

@@ -2504,7 +2504,7 @@
 \pnum
 Class template \tcode{projected} is used to constrain algorithms
 that accept callable objects and projections\iref{defns.projection}.
-It combines a \libconcept{indirectly_readable} type \tcode{I} and
+It combines an \libconcept{indirectly_readable} type \tcode{I} and
 a callable object type \tcode{Proj} into a new \libconcept{indirectly_readable} type
 whose \tcode{reference} type is the result of applying
 \tcode{Proj} to the \tcode{iter_reference_t} of \tcode{I}.
@@ -2557,7 +2557,7 @@
 
 \pnum
 The \libconcept{indirectly_movable} concept specifies the relationship between
-a \libconcept{indirectly_readable} type and a \libconcept{indirectly_writable} type
+an \libconcept{indirectly_readable} type and an \libconcept{indirectly_writable} type
 between which values may be moved.
 
 \begin{codeblock}
@@ -2599,7 +2599,7 @@
 
 \pnum
 The \libconcept{indirectly_copyable} concept specifies the relationship between
-a \libconcept{indirectly_readable} type and a \libconcept{indirectly_writable} type
+an \libconcept{indirectly_readable} type and an \libconcept{indirectly_writable} type
 between which values may be copied.
 
 \begin{codeblock}

source/ranges.tex

@@ -4465,7 +4465,7 @@
 \tcode{as_rvalue_view} presents a view of an underlying sequence
 with the same behavior as the underlying sequence
 except that its elements are rvalues.
-Some generic algorithms can be called with a \tcode{as_rvalue_view}
+Some generic algorithms can be called with an \tcode{as_rvalue_view}
 to replace copying with moving.
 
 \pnum