docs: reorganize sidebars and readd infracost recipe (#438)

## 📝 Description
This change:
- Moves the cache page under the Workflow category
- Creates a recipe category to add integrations with 3rd party tool
- Optimization category has been renamed containers, it only shows
docker-related pages
- The nginx routing config has been updated to maintain the old links
- Reintroduces the infracost integration/recipe page
- Re-enables collapsible categories on the sidebars
- Fixes some rendering issues, `<[email protected]>` caused some
problems with the markdown rendering so I removed the `<>` symbols
- Removed the announcement bar

See #409 for more details

## ✅ Checklist
- [X] I have tested this change
- [ ] This change requires documentation update

Author: TomFern

docs/default.conf

@@ -49,20 +49,23 @@ server {
         application/vnd.ms-fontobject
         image/svg+xml;
 
+	location ~ ^/using-semaphore/optimization/cache?$ {return 301 /using-semaphore/cache;}
+	location ~ ^/using-semaphore/optimization/docker?$ {return 301 /using-semaphore/containers/docker;}
+	location ~ ^/using-semaphore/optimization/container-registry?$ {return 301 /using-semaphore/containers/container-registry;}
 	location ~ ^/account-management/billing-faq/?$ {return 301 /getting-started/faq#billing;}
 	location ~ ^/account-management/connecting-bitbucket-and-semaphore/?$ {return 301 /using-semaphore/connect-bitbucket;}
 	location ~ ^/account-management/connecting-github-and-semaphore/?$ {return 301 /using-semaphore/connect-github;}
 	location ~ ^/account-management/organizations/?$ {return 301 /using-semaphore/organizations;}
 	location ~ ^/account-management/permission-levels/?$ {return 301 /using-semaphore/rbac;}
 	location ~ ^/account-management/working-with-github-sso/?$ {return 301 /using-semaphore/github-sso;}
 	location ~ ^/advanced-ci/flaky-tests/?$ {return 301 /using-semaphore/tests/flaky-tests;}
-	location ~ ^/ci-cd-environment/android-images/?$ {return 301 /using-semaphore/optimization/container-registry#android;}
+	location ~ ^/ci-cd-environment/android-images/?$ {return 301 /using-semaphore/containers/container-registry#android;}
 	location ~ ^/ci-cd-environment/aws-support/?$ {return 301 /using-semaphore/self-hosted-aws;}
 	location ~ ^/ci-cd-environment/choosing-between-a-vm-and-docker-based-environment/?$ {return 301 /using-semaphore/pipelines#docker-environments;}
 	location ~ ^/ci-cd-environment/configure-self-hosted-agent/?$ {return 301 /using-semaphore/self-hosted;}
 	location ~ ^/ci-cd-environment/custom-ci-cd-environment-with-docker/?$ {return 301 /using-semaphore/pipelines#docker-environments;}
-	location ~ ^/ci-cd-environment/docker-authentication/?$ {return 301 /using-semaphore/optimization/docker#auth;}
-	location ~ ^/ci-cd-environment/docker-layer-caching/?$ {return 301 /using-semaphore/optimization/docker#caching;}
+	location ~ ^/ci-cd-environment/docker-authentication/?$ {return 301 /using-semaphore/containers/docker#auth;}
+	location ~ ^/ci-cd-environment/docker-layer-caching/?$ {return 301 /using-semaphore/containers/docker#caching;}
 	location ~ ^/ci-cd-environment/environment-variables/?$ {return 301 /reference/env-vars;}
 	location ~ ^/ci-cd-environment/install-self-hosted-agent/?$ {return 301 /using-semaphore/self-hosted-install;}
 	location ~ ^/ci-cd-environment/job-environment/?$ {return 301 /using-semaphore/jobs;}
@@ -77,19 +80,19 @@ server {
 	location ~ ^/ci-cd-environment/self-hosted-agents-overview/?$ {return 301 /using-semaphore/self-hosted;}
 	location ~ ^/ci-cd-environment/sem-service-managing-databases-and-services-on-linux/?$ {return 301 /reference/toolbox#sem-service;}
 	location ~ ^/ci-cd-environment/sem-version-managing-language-versions-on-linux/?$ {return 301 /reference/toolbox#sem-version;}
-	location ~ ^/ci-cd-environment/semaphore-registry-images/?$ {return 301 /using-semaphore/optimization/container-registry;}
-	location ~ ^/ci-cd-environment/set-up-caching-on-aws-s3/?$ {return 301 /using-semaphore/optimization/cache#aws;}
+	location ~ ^/ci-cd-environment/semaphore-registry-images/?$ {return 301 /using-semaphore/containers/container-registry;}
+	location ~ ^/ci-cd-environment/set-up-caching-on-aws-s3/?$ {return 301 /using-semaphore/containers/cache#aws;}
 	location ~ ^/ci-cd-environment/ubuntu-18.04-image/?$ {return 301 /reference/os-ubuntu;}
 	location ~ ^/ci-cd-environment/ubuntu-20.04-image/?$ {return 301 /reference/os-ubuntu#ubuntu2004;}
 	location ~ ^/ci-cd-environment/ubuntu-22.04-arm-image/?$ {return 301 /reference/os-ubuntu#ubuntu2204-arm;}
 	location ~ ^/ci-cd-environment/ubuntu-22.04-image/?$ {return 301 /reference/os-ubuntu#ubuntu2204-x86;}
-	location ~ ^/ci-cd-environment/working-with-docker/?$ {return 301 /using-semaphore/optimization/docker;}
+	location ~ ^/ci-cd-environment/working-with-docker/?$ {return 301 /using-semaphore/containers/docker;}
 	location ~ ^/article/75-debugging-with-ssh-access/?$ {return 301 /using-semaphore/jobs#ssh-into-agent;}
 	location ~ ^/essentials/artifacts/?$ {return 301 /using-semaphore/artifacts;}
 	location ~ ^/essentials/auto-cancel-previous-pipelines-on-a-new-push/?$ {return 301 /using-semaphore/pipelines#auto-cancel;}
 	location ~ ^/essentials/build-matrix/?$ {return 301 /using-semaphore/jobs#matrix;}
 	location ~ ^/essentials/building-monorepo-projects/?$ {return 301 /using-semaphore/monorepo;}
-	location ~ ^/essentials/caching-dependencies-and-directories/?$ {return 301 /using-semaphore/optimization/cache;}
+	location ~ ^/essentials/caching-dependencies-and-directories/?$ {return 301 /using-semaphore/cache;}
 	location ~ ^/essentials/concepts/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/essentials/configuring-status-checks/?$ {return 301 /using-semaphore/projects#status-checks;}
 	location ~ ^/essentials/debugging-with-ssh-access/?$ {return 301 /using-semaphore/jobs#debug-jobs;}
@@ -204,14 +207,14 @@ server {
 	location ~ ^/examples/laravel-php-continuous-integration/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/netlify-continuous-deployment/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/node-js-and-typescript-continuous-integration/?$ {return 301 /using-semaphore/workflows;}
-	location ~ ^/examples/publishing-docker-images-on-dockerhub/?$ {return 301 /using-semaphore/optimization/docker#auth;}
-	location ~ ^/examples/pushing-docker-images-to-aws-elastic-container-registry-ecr/?$ {return 301 /using-semaphore/optimization/docker#auth;}
-	location ~ ^/examples/pushing-docker-images-to-google-container-registry-gcr/?$ {return 301 /using-semaphore/optimization/docker#auth;}
+	location ~ ^/examples/publishing-docker-images-on-dockerhub/?$ {return 301 /using-semaphore/containers/docker#auth;}
+	location ~ ^/examples/pushing-docker-images-to-aws-elastic-container-registry-ecr/?$ {return 301 /using-semaphore/containers/docker#auth;}
+	location ~ ^/examples/pushing-docker-images-to-google-container-registry-gcr/?$ {return 301 /using-semaphore/containers/docker#auth;}
 	location ~ ^/examples/rails-continuous-integration/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/scala-play-continuous-integration/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/testflight-ios-app-distribution/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/tutorials-and-example-projects/?$ {return 301 /using-semaphore/workflows;}
-	location ~ ^/examples/using-docker-compose-in-ci/?$ {return 301 /using-semaphore/optimization/docker;}
+	location ~ ^/examples/using-docker-compose-in-ci/?$ {return 301 /using-semaphore/containers/docker;}
 	location ~ ^/examples/using-terraform-with-google-cloud/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/examples/zeit-now-continuous-deployment/?$ {return 301 /using-semaphore/workflows;}
 	location ~ ^/faq/migration-guide-for-semaphore-classic-users/?$ {return 301 /using-semaphore/workflows;}