update docs

docs/_navbar.md

@@ -0,0 +1,3 @@
+* [![GitHub stars](https://img.shields.io/github/stars/ehang-io/nps?style=social)](https://github.com/ehang-io/nps/stargazers)
+
+* [![GitHub forks](https://img.shields.io/github/forks/ehang-io/nps?style=social)](https://github.com/ehang-io/nps/network)

docs/index.html

@@ -20,6 +20,7 @@
         repo: '',
         loadSidebar: true,
         coverpage: true,
+        loadNavbar: true,
         subMaxLevel: 2,
         maxLevel: 4,
         search: {