Update 'bash/README.md'

bash/README.md

@@ -8,6 +8,10 @@ Handling command line argument / parameter parsing at the beginning of a script.
 
 How to declare an array, append new elements, iterate over the array for processing.
 
+## associative_array.bash
+
+Numerical arrays are referenced using integers, and associative are referenced using strings. Associative Arrays can be handy when you want the key to have meaning. 
+
 ## booleans.bash
 
 BASH doesn't actually have booleans, but there's tricks to make variables behave enough like bools to be useful.