Update 7.array.md

Changed the line 68 "// Remove and return the last element" to "// Return the first and last elements" based on the original description of `$arrayGet`

Author: Edward-Martinson

guide/Guide/7.array.md

@@ -64,7 +64,7 @@ $arrayPush[Cat]
 $arrayPush[Mouse]
 $arrayPush[Elephant]
 
-// Remove and return the last element
+// Return the first and last elements
 $arrayGet[1], $arrayGet[4]
 ```