Add explanation for count increment operation

Added a comment explaining the increment operation on the count variable.

Author: mrafeie

Sprint-2/1-key-exercises/1-count.js

@@ -4,3 +4,4 @@ count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing
+//adds 1 to the value of count and then = operator stores that value in count variable