Update readme with more details about building and deploying

Author: coreymckrill

README.md

@@ -6,13 +6,19 @@ This project is based on [Slate](https://github.com/tripit/slate).
 
 ## Usage ##
 
-To generate docs run:
+### Updating and building the docs
+
+The docs for the latest version of the REST API (v3) are in `source/includes/wp-api-v3`. Each section of the docs has its own Markdown file. Once you have made changes, you can generate the docs locally with the following:
 
 ```bash
 ./build.sh
 ```
 
-To deploy generated docs:
+After the build script has finished, the generated docs can be found in the `build` directory. Open the `index.html` file in your browser to view the local version of the docs site.
+
+### Deploying the docs
+
+When you merge a PR to the trunk branch of this repository, a workflow runs that will automatically deploy the generated docs to the `gh-pages` branch. However, you can also deploy manually with the following:
 
 ```bash
 ./deploy.sh