refactoring: added comments in main

src/primzahl/main.c

@@ -3,10 +3,13 @@
 #include <stdio.h>
 
 int main() {
+    // set the smallest possible input
     int minInput = 0;
 
+    //get user input
     int num = usergetd("Enter a positive number: ", minInput, NULL);
 
+    //check if its a prime number or not
     if (primzahl(num))
         printf("%d is a prime number.\n", num);
     else