Add example how to compress a folder.

README.md

@@ -172,6 +172,38 @@ for (i = 0; i < n; ++i) {
 zip_close(zip);
 ```
 
+* Compress folder (recursively)
+```c
+void zip_walk(struct zip_t *zip, const char *path) {
+    DIR *dir;
+    struct dirent *entry;
+    char fullpath[MAX_PATH];
+    struct stat s;
+
+    memset(fullpath, 0, MAX_PATH);
+    dir = opendir(path);
+    assert(dir);
+
+    while ((entry = readdir(dir))) {
+      // skip "." and ".."
+      if (!strcmp(entry->d_name, ".\0") || !strcmp(entry->d_name, "..\0"))
+        continue;
+
+      snprintf(fullpath, sizeof(fullpath), "%s/%s", path, entry->d_name);
+      stat(path, &s);
+      if (S_ISDIR(s.st_mode))
+        zip_walk(zip, fullpath);
+      else {
+        zip_entry_open(zip, fullpath);
+        zip_entry_fwrite(zip, fullpath);
+        zip_entry_close(zip);
+      }
+    }
+
+    closedir(dir);
+}
+```
+
 # Bindings
 Compile zip library as a dynamic library.
 ```shell