Replace content & config with tech-docs version

This change converts the site to use (a patched
version of) the gov.uk tech-docs template & gems.

https://github.com/alphagov/tech-docs-template

Details of the patch are here:
ministryofjustice/cloud-platform-user-guide#393

This gives the site a search feature, as well as
dynamic review dates (i.e. you see a big red
banner at the foot of the page if the content was
not reviewed when it should have been).

Publishing is now done via a github action. See:

.github/workflows/publish.yml

...for details.

.github/workflows/publish.yml

@@ -0,0 +1,27 @@
+name: Publish
+
+on:
+  push:
+    branches:
+      - "main"
+    paths-ignore:
+      - "docs/**"
+
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    container:
+      image: ministryofjustice/cloud-platform-tech-docs-publisher:1.1
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build
+      run: bundle exec middleman build --build-dir docs --relative-links
+      env:
+        ROOT_DOCPATH: /technical-guidance
+    - run: touch docs/.nojekyll
+    - run: git config --global user.email "[email protected]"
+    - run: git config --global user.name "Github Action"
+    - run: git checkout -b gh-pages
+    - run: git add docs
+    - run: git commit -m "Published at $(date)"
+    - run: git push origin gh-pages --force

Gemfile

@@ -1,7 +1,14 @@
+# If you do not have OpenSSL installed, change
+# the following line to use 'http://'
 source 'https://rubygems.org'
 
-gem 'github-pages', group: :jekyll_plugins
+# For faster file watcher updates on Windows:
+gem 'wdm', '~> 0.1.0', platforms: [:mswin, :mingw]
 
-group :development do
-  gem 'ministryofjustice-danger'
-end
+# Windows does not come with time zone data
+gem 'tzinfo-data', platforms: [:mswin, :mingw, :jruby]
+
+# Include the tech docs gem
+gem 'govuk_tech_docs'
+
+gem "html-proofer"