readme updated

Author: MohiuddinRabby

README.md

@@ -1 +1,21 @@
 # JS-array
+#### arrays are used to store multiple values in a single variable
+
+> declare an array
+
+```js
+const arr = []
+//arr is a variable where an empty array been declared
+arr[0] = 1;
+//declared 1 as a value of index 0 
+arr[1] = 2;
+arr[2] = 3;
+arr[3] = 5;
+console.log(arr.length) //arr.length gives the length of arr
+//output: 4
+console.log(arr)
+//output:: [1,2,3,5]
+arr[10] = 11;
+console.log(arr)
+//output: [ 1, 2, 3, 5, <6 empty items>, 11 ]
+```