subject(communmultiple):add readme

subjects/commonmultiples/README.md

@@ -0,0 +1,42 @@
+## common-multiples
+
+### Instructions
+
+Write a function to check whether a given non-negative number is a multiple of 3 or 7.
+- If the number is a multiple of 3 or 7, return `true`.
+- If the number is not a multiple of 3 or 7, return `false`.
+- If the number is less or equal to 0, return `false`.
+
+### Expected function
+
+```go
+func IsMultiple(number int) bool {
+    // Your code here
+}
+```
+
+### Usage
+```go
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println(IsMultiple(3))
+    fmt.Println(IsMultiple(7))
+    fmt.Println(IsMultiple(8))
+    fmt.Println(IsMultiple(9))
+    fmt.Println(IsMultiple(-1))
+}
+```
+
+and the output should be:
+
+```console
+$ go run .
+true
+true
+false
+false
+false
+```