doc(README): add format_m description

Damian Rouson · Damian Rouson · commit c3c60a17afd2 · 2021-09-27T23:46:45.000-07:00
diff --git a/README.md b/README.md
@@ -48,6 +48,7 @@ Contents
 * Array functions
 * String functions
 * User-defined collective subroutines
+* Input/output format strings and format string generators
 
 ### Classes
 * Parallel data partitioning and gathering,
