add note about adding tst_grow_header.c

Author: wkliao

sneak_peek.md

@@ -73,7 +73,8 @@ This is essentially a placeholder for the next release note ...
     See [PR #165](https://github.com/Parallel-NetCDF/PnetCDF/pull/165).
 
 * New test program
-  + none
+  + test/testcases/tst_grow_header.c tests header extent growth by re-entering
+    the define mode multiple times and add more fix-sized and record variables.
 
 * Issues with NetCDF library
   + none

test/testcases/tst_grow_header.c

@@ -1,13 +1,12 @@
 /*
  *  Copyright (C) 2025, Northwestern University and Argonne National Laboratory
  *  See COPYRIGHT notice in top-level directory.
- *
  */
 
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  *
- * This program tests header extent growth by re-entering the define mode and
- * add more fix-sized and record variables.
+ * This program tests header extent growth by re-entering the define mode
+ * multiple times and add more fix-sized and record variables.
  *
  * The compile and run commands are given below.
  *