all: index accessor in array init expression (#12181)

doc/docs.md

@@ -692,6 +692,14 @@ arrays there is a second initialization syntax:
 ```v
 mut a := []int{len: 10000, cap: 30000, init: 3}
 ```
+
+You can initialize the array by accessing the it variable as shown here:
+
+```v
+mut square := []int{len: 6, init: it * it}
+// square == [0, 1, 4, 9, 16, 25]
+```
+
 This creates an array of 10000 `int` elements that are all initialized with `3`. Memory
 space is reserved for 30000 elements. The parameters `len`, `cap` and `init` are optional;
 `len` defaults to `0` and `init` to the default initialization of the element type (`0`