Document that k8s 1.22 is the minimum required

This updates all references of Kubernetes 1.21 as necessary,
including the command for setting up K8s cluster.

Signed-off-by: Vincent Demeester <[email protected]>

DEVELOPMENT.md

@@ -267,7 +267,7 @@ as follows.
 
 The recommended minimum development configuration is:
 
-- Kubernetes version 1.21 or later
+- Kubernetes version 1.22 or later
 - 4 (virtual) CPU nodes
   - 8 GB of (actual or virtualized) platform memory
 - Node autoscaling, up to 3 nodes
@@ -326,7 +326,7 @@ optional: As a convenience, the [Tekton plumbing project](https://github.com/tek
      --machine-type=n1-standard-4 \
      --image-type=cos \
      --num-nodes=1 \
-     --cluster-version=1.21
+     --cluster-version=1.22
     ```
 
     > **Note**: The recommended [GCE machine type](https://cloud.google.com/compute/docs/machine-types) is `'n1-standard-4'`.

docs/api-spec.md

@@ -42,7 +42,7 @@ This document makes reference in a few places to different profiles for Tekton i
 
 The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” are to be interpreted as described in [RFC 2119](https://tools.ietf.org/html/rfc2119).
 
-There is no formal specification of the Kubernetes API and Resource Model. This document assumes Kubernetes 1.21 behavior; this behavior will typically be supported by many future Kubernetes versions. Additionally, this document may reference specific core Kubernetes resources; these references may be illustrative (i.e. an implementation on Kubernetes) or descriptive (i.e. this Kubernetes resource MUST be exposed). References to these core Kubernetes resources will be annotated as either illustrative or descriptive.
+There is no formal specification of the Kubernetes API and Resource Model. This document assumes Kubernetes 1.22 behavior; this behavior will typically be supported by many future Kubernetes versions. Additionally, this document may reference specific core Kubernetes resources; these references may be illustrative (i.e. an implementation on Kubernetes) or descriptive (i.e. this Kubernetes resource MUST be exposed). References to these core Kubernetes resources will be annotated as either illustrative or descriptive.
 
 ## Modifying This Specification
 

docs/install.md

@@ -32,7 +32,7 @@ This guide explains how to install Tekton Pipelines. It covers the following top
 
 ## Before you begin
 
-1. You must have a Kubernetes cluster running version 1.21 or later.
+1. You must have a Kubernetes cluster running version 1.22 or later.
 
    If you don't already have a cluster, you can create one for testing with `kind`.
    [Install `kind`](https://kind.sigs.k8s.io/docs/user/quick-start/#installation) and create a cluster by running [`kind create cluster`](https://kind.sigs.k8s.io/docs/user/quick-start/#creating-a-cluster). This
@@ -396,9 +396,9 @@ use of custom tasks in pipelines.
 most stable features to be used. Set it to "alpha" to allow [alpha
 features](#alpha-features) to be used.
 
-- `embedded-status`: set this flag to "full" to enable full embedding of `TaskRun` and `Run` statuses in the 
+- `embedded-status`: set this flag to "full" to enable full embedding of `TaskRun` and `Run` statuses in the
  `PipelineRun` status. Set it to "minimal" to populate the `ChildReferences` field in the `PipelineRun` status with
-  name, kind, and API version information for each `TaskRun` and `Run` in the `PipelineRun` instead. Set it to "both" to 
+  name, kind, and API version information for each `TaskRun` and `Run` in the `PipelineRun` instead. Set it to "both" to
   do both. For more information, see [Configuring usage of `TaskRun` and `Run` embedded statuses](pipelineruns.md#configuring-usage-of-taskrun-and-run-embedded-statuses).
 
 For example: