[diff.cpp20.utilities] Rephrase to avoid undefined term 'const-iterable'

Author: jensmaurer

source/compatibility.tex

@@ -81,7 +81,9 @@
 Signature changes: \tcode{format}, \tcode{format_to}, \tcode{format_to_n},
 \tcode{formatted_size}.
 \rationale
-Enable formatting of views that are neither const-iterable nor copyable.
+Enable formatting of views
+that do not support iteration when const-qualified and
+are not copyable.
 \effect
 Valid \CppXX{} code that passes bit fields to formatting functions
 may become ill-formed. For example: