doc(README): add ASCII art

Author: rouson

README.md

@@ -1,6 +1,12 @@
 Julienne
 ========
-
+```
+     _       _ _                       
+    | |_   _| (_) ___ _ __  _ __   ___ 
+ _  | | | | | | |/ _ \ '_ \| '_ \ / _ \
+| |_| | |_| | | |  __/ | | | | | |  __/
+ \___/ \__,_|_|_|\___|_| |_|_| |_|\___|
+ ```
 Julienne is a modern Fortran unit-testing framework that includes utilities for manipulating strings 
 via Julienne's `string_t` derived type.  The target strings include command-line arguments accessed
 via Julienne's `command_line_t` type  and format strings generated by functions in Julienne's `formats_m` module.