chore: add MIT license headers and author attribution to all source files

rkeytable.c

@@ -1,12 +1,21 @@
+// Written by retoor@molodetz.nl
+
+// This code generates random keys and stores them in a key-value store, then asserts that the retrieved value matches the expected value
+// "tast".
+
+// Includes: rkeytable.h, rtest.h, rstring.h
+
+// MIT License
+
 #include "rkeytable.h"
 #include "rtest.h"
 #include "rstring.h"
 
 int main() {
-
     for (int i = 0; i < 1000; i++) {
         char *key = rgenerate_key();
         rkset(key, "tast");
         rasserts(!strcmp(rkget(key), "tast"));
     }
+    return 0;
 }