Remove paas Github environments

They were still referenced in some places. The new environments are only
the *_aks ones.

.github/workflows/manual.yml

@@ -72,7 +72,7 @@ jobs:
            azure-credentials: ${{ secrets.AZURE_CREDENTIALS }}
 
        - name: Slack Release Notification
-         if: steps.tag_id.outputs.release_id && github.event.inputs.environment == 'Production'
+         if: steps.tag_id.outputs.release_id && github.event.inputs.environment == 'production_aks'
          uses: rtCamp/action-slack-notify@master
          env:
            SLACK_COLOR:    ${{env.SLACK_SUCCESS}}

.github/workflows/trello.yml

@@ -8,7 +8,7 @@ jobs:
     name: Link Trello card to this PR
     if: "!contains( 'dependabot[bot] snyk-bot' , github.actor )"
     runs-on: ubuntu-latest
-    environment: Development
+    environment: development_aks
     steps:
       - uses: Azure/login@v1
         with:

README.md

@@ -125,7 +125,7 @@ The API is deployed to [AKS](https://github.com/DFE-Digital/teacher-services-clo
 
 ### Process
 
-When you merge a branch to `master` it will automatically be deployed to the [development](#environments) and [test](#environments) environments via GitHub Actions and a tagged release will be created (the tag will use the PR number). You can then test the changes using the corresponding dev/test environments of the other GiT services. Once you're happy and want to ship to [production](#environments) you need to note the tag of your release and go to the `Manual Release` GitHub Action; from there you can select `Run workflow`, choose the `Production` environment and enter your release number.
+When you merge a branch to `master` it will automatically be deployed to the [development](#environments) and [test](#environments) environments via GitHub Actions and a tagged release will be created (the tag will use the PR number). You can then test the changes using the corresponding dev/test environments of the other GiT services. Once you're happy and want to ship to [production](#environments) you need to note the tag of your release and go to the `Manual Release` GitHub Action; from there you can select `Run workflow`, choose the `production_aks` environment and enter your release number.
 
 ### Rollbacks