[mdspan.submdspan.*] Change "Let .. name the type" to "Let ... be" for consistency

Author: burblebee

source/containers.tex

@@ -21654,7 +21654,7 @@
 \tcode{Extents} is a specialization of \tcode{extents}.
 
 \pnum
-Let \tcode{index_type} name the type \tcode{typename Extents::index_type}.
+Let \tcode{index_type} be \tcode{typename Extents::index_type}.
 
 %FIXME: What is $k$ in this itemdescr? Don't we want \tcode{k} and not $k$?
 \pnum
@@ -21848,7 +21848,7 @@
 
 \begin{itemdescr}
 \pnum
-Let \tcode{index_type} name the type \tcode{typename Extents::index_type}.
+Let \tcode{index_type} be \tcode{typename Extents::index_type}.
 
 \pnum
 \constraints
@@ -21982,7 +21982,7 @@
 
 \begin{itemdescr}
 \pnum
-Let \tcode{index_type} name the type \tcode{typename Extents::index_type}.
+Let \tcode{index_type} be \tcode{typename Extents::index_type}.
 
 \pnum
 Let \tcode{sub_map_offset} be the result of