Add disable-affinity-assistant feature flag to config

This feature flag is implemented, but was not added to the
config-feature-flags.yaml file

/kind misc

config/config-feature-flags.yaml

@@ -21,6 +21,15 @@ metadata:
     app.kubernetes.io/instance: default
     app.kubernetes.io/part-of: tekton-pipelines
 data:
+  # Setting this flag to "true" will prevent Tekton to create an
+  # Affinity Assistant for every TaskRun sharing a PVC workspace
+  #
+  # The default behaviour is for Tekton to create Affinity Assistants
+  #
+  # See more in the workspace documentation about Affinity Assistant
+  # https://github.com/tektoncd/pipeline/blob/master/docs/workspaces.md#affinity-assistant-and-specifying-workspace-order-in-a-pipeline
+  # or https://github.com/tektoncd/pipeline/pull/2630 for more info.
+  disable-affinity-assistant: "false"
   # Setting this flag to "true" will prevent Tekton overriding your
   # Task container's $HOME environment variable.
   #