Add initial draft of runbook to deploy to a specific environment

Part of gitlab-com/gl-infra/delivery#2143 (closed)

This runbook covers how to explicitly deploy to an individual environment in the exceptional circumstances that it is needed. Also includes things to consider due to the pipeline reorder.

runbooks/deploy-to-a-single-environment.md

-# Deploying to a single environment
+# How to deploy to a single environment?
 
-This runbook aims to cover the use cases where our auto-deploy pipelines are
-not functioning correctly, or there is a need to deploy to environments out of
-order, and thus you need to manually deploy a specific release to an environment.
+This runbook aims to cover the use cases where our coordinated pipelines pipelines
+are not functioning correctly, and thus you need to manually deploy a specific release to an environment.
 
 ## Pre-deploy considerations
 
-* When deploying to a canary environment, make sure canary is unddrained so
-that QA tests are accurately using the canary stage
-
-* Identify the full package version you wish to deploy using XXX
+* Packages on `gstg` and `gprd` should be kept in sync, if you need to manually deploy 
+to one of these environments, it'd be required to also deploy to other one as well.
+* When deploying to a canary environment, make sure [canary is undrained] so
+that QA tests are accurately using the canary stage.
 
 ## Deploying to a single environment
 
-* Use chatops to deploy to a single environment
-
-```
-# Staging deploy
-/chatops run deploy 14.X.XXX
-
-# Staging canary deploy
-/chatops run deploy --canary 14.X.XXX
-
-# Production deploy
-/chatops run deploy --production 14.X.XXX
-
-# Production canary deploy
-/chatops run deploy --production --canary 14.X.XXX
-```
+1. Identify the auto-deploy package version you wish to deploy. You can grab the package
+  from the `#announcements` channel.
+2. Use chatops to deploy to a single environment:
 
-## Post-deploy considerations
+| Environment | ChatOps command |
+| --- | --- |
+| staging           | `/chatops run deploy 14.9.202203101220-571badda7c4.4e8301d17e3` |
+| staging-canary    | `/chatops run deploy --canary 14.9.202203101220-571badda7c4.4e8301d17e3` |
+| production        | `/chatops run deploy --production 4.9.202203101220-571badda7c4.4e8301d17e3` | 
+| canary-production | `/chatops run deploy --production --canary 4.9.202203101220-571badda7c4.4e8301d17e3` |
 
-* If you are deploying to `gstg` or `gprd`, consider the fact that the pipeline
-order expects that these environments are kept very close in sync. If you manually
-deploy to a single environment, you should highly consider manually deploying
-to the other one as well
+[canary is undrained]: https://about.gitlab.com/handbook/engineering/infrastructure/environments/canary-stage/#re-enabling-canary-stage-in-an-environment