Style example output and errors in the docs.

doc/site/core/system.markdown

@@ -16,7 +16,7 @@ Prints [object] to the console followed by a newline. If not already a string,
 the object is converted to a string by calling `toString` on it.
 
     :::wren
-    System.print("I like bananas") // Prints "I like bananas".
+    System.print("I like bananas") //> I like bananas
 
 ### System.**printAll**(sequence)
 
@@ -24,7 +24,7 @@ Iterates over [sequence] and prints each element, then prints a single newline
 at the end. Each element is converted to a string by calling `toString` on it.
 
     :::wren
-    System.printAll([1, [2, 3], 4]) // Prints "1[2, 3]4".
+    System.printAll([1, [2, 3], 4]) //> 1[2, 3]4
 
 ### System.**write**(object)
 
@@ -32,7 +32,7 @@ Prints a single value to the console, but does not print a newline character
 afterwards. Converts the value to a string by calling `toString` on it.
 
     :::wren
-    System.write(4 + 5) // Prints "9".
+    System.write(4 + 5) //> 9
 
 In the above example, the result of `4 + 5` is printed, and then the prompt is
 printed on the same line because no newline character was printed afterwards.