update README.md (#251)

Co-authored-by: 呈铭 <[email protected]>

README.md

@@ -4,6 +4,51 @@ Source for mosn.io site <https://mosn.io>.
 
 Powered by [hugo](https://gohugo.io) with [docsy theme](https://github.com/google/docsy).
 
-## Notice
+# Install Hugo
+
+You need a [recent extended version](https://github.com/gohugoio/hugo/releases) (we recommend version 0.53 or later) of [Hugo](https://gohugo.io/) to do local builds and previews of sites (like this one) that use Docsy. If you install from the release page, make sure to get the `extended` Hugo version, which supports [SCSS](https://sass-lang.com/documentation/file.SCSS_FOR_SASS_USERS.html); you may need to scroll down the list of releases to see it.
+
+For comprehensive Hugo documentation, see [gohugo.io](https://gohugo.io/).
+
+# Environment setup
+You can follow the manual steps given below.
+
+1. Ensure pre-requisites are installed 
+2. Clone this repository
+
+```
+git clone [email protected]:mosn/mosn.io.git
+```
+
+3. Install `PostCSS` required by Docsy by running the following commands from the root directory of your project:
+
+```
+npm install --save-dev autoprefixer
+npm install -D postcss
+npm install --save-dev postcss-cli
+```
+
+# Run server locally
+1. Clear up your local module cache
+
+```
+hugo mod clean
+```
+
+2. Start the server
+
+```
+hugo server --disableFastRender
+```
+
+3. Navigate to `http://localhost:1313`
+
+# Update docs
+1. Create new branch 
+2. Commit and push changes to content 
+3. Submit pull request to master branch 
+4. Staging site will automatically get created and linked to PR to review and test
+
+# Notice
 
 This website is built under hugo version v0.55.5-A83256B9C/extended. There may be unknown errors when compiling on other versions.