Bump Nextra version and update readme (#212)

* bump nextra version; update readme

* upgrade nextra

* upgrade nextra

Author: shuding

README.md

@@ -2,11 +2,11 @@
 
 The official website for [SWR](https://github.com/vercel/swr).
 
-To develop locally, clone this repository and run the following command to start the local dev server:
+The project uses [pnpm](https://pnpm.io), [Nextra](https://nextra.vercel.app) and deploys via [Vercel](https://vercel.com). To develop it locally, clone this repository and run the following command to start the local dev server:
 
 ```bash
-yarn
-yarn dev
+pnpm install
+pnpm dev
 ```
 
 And visit `localhost:3000` to preview your changes.

package.json

@@ -17,8 +17,8 @@
     "intersection-observer": "^0.10.0",
     "markdown-to-jsx": "^6.11.4",
     "next": "^12.0.7",
-    "nextra": "^2.0.0-alpha.12",
-    "nextra-theme-docs": "^2.0.0-alpha.12",
+    "nextra": "^2.0.0-alpha.16",
+    "nextra-theme-docs": "^2.0.0-alpha.16",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",
     "react-intersection-observer": "^8.26.2"