itoabase exam exercise readme

subjects/itoabase.en.md

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+## itoabase
+
+### Instructions
+
+Write a function that converts an integer value to a null-terminated string
+using the specified base and stores the result in a char array that you must
+allocate.
+
+The base is expressed as an integer, from 2 to 16. The characters comprising
+the base are the digits from 0 to 9, followed by uppercase letter from A to F.
+
+For example, base 4 would be "0123" and base 16 "0123456789ABCDEF".
+
+If base is 10 and value is negative, the resulting string is preceded with a
+minus sign (-). With any other base, value is always considered unsigned.
+
+### Expected function
+
+```go
+func ItoaBase(value, base int) string {
+
+}
+```