Mention zstd as supported in ziptool.
diff --git a/src/ziptool.c b/src/ziptool.c
index 0c28bde..125c1a7 100644
--- a/src/ziptool.c
+++ b/src/ziptool.c
@@ -841,6 +841,9 @@
     if (zip_compression_method_supported(ZIP_CM_XZ, 1)) {
 	fprintf(out, "\txz\n");
     }
+    if (zip_compression_method_supported(ZIP_CM_ZSTD, 1)) {
+	fprintf(out, "\tzstd\n");
+    }
     fprintf(out, "\nSupported encryption methods are:\n"
 	    "\tnone\n");
     if (zip_encryption_method_supported(ZIP_EM_AES_128, 1)) {