Update Hugo version and improve documentation setup guide

Updated the CI workflow to use Hugo 0.140.2 for building the site. Added details in the README on installing Hugo and running the documentation site locally with clear instructions.

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Setup Hugo
         uses: peaceiris/actions-hugo@v2
         with:
-          hugo-version: '0.135.0'
+          hugo-version: '0.140.2'
       - name: Run hugo
         run: |
           echo $PWD

README.md

@@ -1 +1,22 @@
 # https://docs.duendesoftware.com
+
+## Getting Started
+
+You will need [**Hugo 0.140.2**](https://gohugo.io/) installed on your operating system and in the PATH. 
+
+See the [official Hugo documentation](https://gohugo.io/installation/) for OS-specific instructions.
+
+## Running the Documentation Site(s)
+
+There are several versions of documentation in the repository, and they all operate similarly. 
+
+Any directory containing a `config.toml` file is a Hugo instance, and can be interacted with 
+using hugo commands. To launch a site use the `hugo serve` command. To launch the latest
+documentation site, use the following commands in a terminal from the root directory.
+
+```bash
+cd ./IdentityServer/v7/docs
+hugo serve
+```
+
+See the output for the running documentation site, typically at `http://localhost:1313/identityserver/v7/`.