subject(camelTosnackCase): add readme

subjects/cameltosnakecase/README.md

@@ -0,0 +1,43 @@
+## Camel-to-snake-case 
+
+### Instructions
+
+Write a function that converts a string from a camel case to a snake case.
+- If the string is empty, return an empty string.
+- If the string is not a camel case, return the string unchanged.
+- If the string is a camel case, return the snake case version of the string.
+
+### Expected function 
+```go
+func CamelToSnakeCase(s string) string{
+    //Your code here
+}
+```
+
+### Usage 
+
+```go
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println(CamelToSnakeCase("HelloWorld")) 
+    fmt.Println(CamelToSnakeCase("heloWorld"))
+    fmt.Println(CamelToSnakeCase("CamelToSnakeCase"))
+    fmt.Println(CamelToSnakeCase("132322"))
+    fmt.Println(CamelToSnakeCase(""))
+}
+```
+
+and the output should be:
+
+```console
+$ go run . | cat -e
+Hello_World$
+helo_World$
+Camel_To_Snake_Case$
+132322$
+$
+```
+