update readme with complexities

Author: Nibba2018

C/Program-Timer/README.md

@@ -7,6 +7,8 @@ This script checks the time required to run a function in C.
 * Compile with `gcc timer.c -o timer`.
 * Execute with `./timer`
 
+**Time Complexity:** O(1)
+**Space Complexity:** 0(1)
 
 ## Output
 ![output](output.png)