diff --git a/README.md b/README.md
index 5d17eb477a..df3356a558 100644
--- a/README.md
+++ b/README.md
@@ -4,46 +4,54 @@
 
 This is a static site generated with Middleman, using [alphagov/tech-docs-template](https://github.com/alphagov/tech-docs-template).
 
-Some of the files (like the CSS, javascripts and layouts) are managed in the template and are not supposed to be modified here. Any project-specific
-Ruby code needs to go into `/app`.
+Some of the files (like the CSS, javascripts and layouts) are managed in the template and are not supposed to be modified here. Any project-specific Ruby code needs to go into `/app`.
 
-## Build the app locally
+## Run the app locally
 
-```sh
-bundle install
-```
+Run govuk-developer-docs either inside or outside govuk-docker, configuring its behaviour with the ENV variables below.
 
-## Run the tests locally
+### ENV variables
 
-```
-bundle exec rake
-```
+- `GITHUB_TOKEN=<your private token>` - token to use to make authenticated requests to GitHub's API. Authenticated requests have a much higher rate limit. *You _will_ need to specify a `GITHUB_TOKEN` if you want to build the entire Developer Docs site*. [Create the token on GitHub](https://github.com/settings/tokens/new) (the token doesn't need any scopes).
+- `SKIP_PROXY_PAGES=true` - avoid fetching remote 'docs/' for each repo (i.e. just build the docs that live within govuk-developer-docs itself). You can use this if you don't have a `GITHUB_TOKEN` or if you don't care about including the remote docs.
+- `NO_CONTRACTS=true` - [recommended setting](https://github.com/alphagov/govuk-developer-docs/commit/4b624a72761490c8e9b99a1aa7a10371415381e6) for speeding up the site build process
 
-## Run the app locally
+### Run with govuk-docker
 
-```sh
-SKIP_PROXY_PAGES=true ./startup.sh
+govuk-docker doesn't have great support for passing ENV vars into the application startup. You'll need to [edit the docker-compose.yml](https://github.com/alphagov/govuk-docker/blob/ed98d3547708286f534598c78fb5c57ee3c8d112/projects/govuk-developer-docs/docker-compose.yml#L12-L17) to add the necessary ENV vars (e.g. `GITHUB_TOKEN`) under the `environment` property for both the `govuk-developer-docs-app` and `govuk-developer-docs-lite` groups, eg:
+
+```yml
+   environment:
+      GITHUB_TOKEN: "<fill it in>"
 ```
 
-## Proxy pages
+1. In govuk-docker:
+  1. Edit `govuk-docker/projects/govuk-developer-docs/docker-compose.yml` as above
+  1. [make the project](https://docs.publishing.service.gov.uk/repos/govuk-docker.html#usage)
+1. In govuk-developer-docs:
+  1. Install the dependencies (`govuk-docker-run bundle install`)
+  1. Run the application (`govuk-docker-up`)
+  1. Wait until all the GitHub API calls have completed (you'll see `Inspect your site configuration at` in the output). This can take a few minutes.
+1. Visit <http://govuk-developer-docs.dev.gov.uk/>
 
-The live docs site includes pages from other alphagov GitHub repositories. To test this locally, omit `SKIP_PROXY_PAGES=true` from the command above.
+### Run without govuk-docker
 
-The app downloads these "proxy pages" at startup and this can cause GitHub to rate limit your requests. You can pass a valid GitHub API token to the app to help avoid this:
+1. Install the dependencies (`bundle install`)
+1. Start up the site with `./startup.sh` (passing ENV vars on the CLI if necessary)
 
-1. [Create a GitHub token](https://github.com/settings/tokens/new). The token doesn't need any scopes.
+## Building the project, and running tests
 
-1. Store the token in a `.env` file:
+If you just want to create the site (a `build/` directory containing a set of HTML files), but not actually start up the application, you can do so as follows (again, the ENV variables described above apply here too):
 
-    ```sh
-    GITHUB_TOKEN=somethingsomething
-    ```
+```sh
+NO_CONTRACTS=true bundle exec middleman build --verbose
+```
 
-1. Start the application:
+To run the tests:
 
-    ```sh
-    ./startup.sh
-    ```
+```
+bundle exec rake
+```
 
 ## Update to the latest Tech Docs template
 
@@ -58,14 +66,6 @@ We host GOV.UK Developer Docs as a static site on GitHub Pages. The [ci.yml] Git
 - when a PR is merged to the default branch
 - on an hourly schedule, to pick up changes to docs included from other repos
 
-### Build the static site locally
-
-```sh
-NO_CONTRACTS=true bundle exec middleman build
-```
-
-This will create a `build` directory containing a set of HTML files.
-
 ## Licence
 
 [MIT License](LICENCE)
diff --git a/app/document_types.rb b/app/document_types.rb
index 8314cbfe15..a4dfaeac24 100644
--- a/app/document_types.rb
+++ b/app/document_types.rb
@@ -80,6 +80,8 @@ def shift_low_value_schemas(schemas)
         generic_with_external_links
         placeholder
       ].each do |low_value_schema|
+        raise "Error building document-types page. Is ~/govuk/publishing-api is up to date?" if schemas.nil?
+
         if schemas.include?(low_value_schema)
           schemas.delete(low_value_schema)
           schemas.append(low_value_schema)