Clarify the strftime module's purpose.

diff --git a/doc/functions/strftime.texi b/doc/functions/strftime.texi
index 5b297bd..8b579be 100644 (file)
--- a/doc/functions/strftime.texi
+++ b/doc/functions/strftime.texi
@@ -13,3 +13,6 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @end itemize
+
+Extension: Gnulib offers a module @samp{strftime} that provides an
+@code{strftime} function with various GNU extensions.