feat(README): update the readme

README.md

@@ -7,7 +7,8 @@ Example of working with a singly linked list (sll):
 ```c
 char *a = "one";
 char *b = "two";
-ds_sll_t *ll = ds_sll_new_node(a); // [ "one" ]
+ds_sll_t *ll = ds_sll_init();
+ds_sll_insert(ll, a); // [ "one" ]
 ds_sll_insert(ll, b); // [ "one", "two" ]
 ds_ll_foreach(ds_sll_t, ll) {
     puts(cur->data);
@@ -22,28 +23,28 @@ datatypes.
 
 ## Hash Map
 ```c
-struct complex {
+typedef struct {
     int num;
     char *str;
-};
+} complex ;
 
-struct complex *a = calloc(1, sizeof(struct complex));
+complex *a = calloc(1, sizeof(complex));
 a->num = 1;
 a->str = "abc";
-struct complex *b = calloc(1, sizeof(struct complex));
+complex *b = calloc(1, sizeof(complex));
 b->num = 2;
 b->str = "def";
 
 ds_hmp_t *hmp = ds_hmp_init(101);
 ds_hmp_insert(hmp, a->str, a); // [ (23)[ [ a->str, a ] ] ]
 ds_hmp_insert(hmp, b->str, b); // [ (23)[ [ a->str, a ] ], (58)[ [ b->str, b ] ]
-struct complex *pa = ds_hmp_remove(hmp, a->str); // a
+complex *pa = ds_hmp_remove(hmp, a->str); // a
 free(pa->str);
 free(pa);
-ds_hmp_free(&hmp);
+ds_hmp_free(&hmp, NULL);
 free(b);
 ```
 
 # TODO
 - [ ] more data structures
-- [ ] tests
+- [x] tests