Added README file.

README.md

@@ -0,0 +1,81 @@
+Introduction
+============
+
+**LibHashSet** is a simple *hash set* implementation for C99. It uses open addressing and double hashing.
+
+At this time, the *only* type of elements (keys) supported is `uint64_t`.
+
+This hash set implementation has been tested to *efficiently* handle several billions of items 😏
+
+
+Getting Started
+===============
+
+Here is a simple example of how to use LibHashSet in your application:
+
+```C
+#include <hash_set.h>
+#include <stdio.h>
+
+int main(int argc, char* argv[])
+{
+	size_t offset = 0U;
+	uint64_t value;
+
+	/* create new hash set instance */
+	hash_set_t *const hash_set = hash_set_create(0U, -1.0, 0U);
+	if (!hash_set)
+	{
+		fputs("Allocation has failed!\n", stderr);
+		return EXIT_FAILURE;
+	}
+
+	/* add a number of items to the hash set, the set will grow as needed */
+	while (have_more_items())
+	{
+		const errno_t error = hash_set_insert(hash_set, get_next_item());
+		if (error)
+		{
+			fprintf(stderr, "Insert operation has failed! (error: %d)\n", error);
+			return EXIT_FAILURE;
+		}
+	}
+
+	/* test whether hash set contains a specific item */
+	if (hash_set_contains(hash_set, 42U) == 0)
+	{
+		puts("Set contains item!");
+
+		/* remove the existing item from the hash set */
+		if (hash_set_remove(hash_set, 42U) == 0)
+		{
+			puts("Item has been removed!");
+		}
+	}
+
+	/* print total number of items in the hash set*/
+	printf("Total number of items: %zu\n", hash_set_size(hash_set));
+
+	/* print all items in the set */
+	while (hash_set_iterate(hash_set, &offset, &value) == 0)
+	{
+		printf("Item: %016llX\n", value);
+	}
+
+	/* destroy the hash set, when it is no longer needed! */
+	hash_set_destroy(hash_set);
+	return EXIT_SUCCESS;
+}
+```
+
+
+License
+=======
+
+This work has been released under the **CC0 1.0 Universal** license.
+
+For details, please refer to:  
+<https://creativecommons.org/publicdomain/zero/1.0/legalcode>
+
+
+&marker;

hashset/src/main.c

@@ -288,7 +288,7 @@ static int test_function_3(hash_set_t *const hash_set)
 /* MAIN                                                                      */
 /* ========================================================================= */
 
-int main()
+int main(void)
 {
 	hash_set_t *const hash_set = hash_set_create(0U, -1.0, 0U /*HASHSET_OPT_FAILFAST*/);
 	if (!hash_set)