[release-1.2] Add upgrade commands for homebrew (#4722)

* Add upgrade commands for homebrew

* lint

* Apply feedback

* Apply feedback

Co-authored-by: snneji <snneji@vmware.com>

docs/getting-started/quickstart-install.md

@@ -6,7 +6,8 @@ the Knative `quickstart` plugin.
 The plugin installs a preconfigured Knative deployment on a local Kubernetes cluster.
 
 !!! warning
-    Knative `quickstart` environments are for experimentation use only. For a production ready installation, see [Installing Knative](../install/README.md).
+    Knative `quickstart` environments are for experimentation use only.
+    For a production ready installation, see [Installing Knative](../install/README.md).
 
 ## Before you begin
 
@@ -25,12 +26,18 @@ Before you can get started with a Knative `quickstart` deployment you must intst
 To get started, install the Knative `quickstart` plugin:
 
 === "Using Homebrew"
-    For macOS, you can install the `quickstart` plugin by using [Homebrew](https://brew.sh){target=_blank}:
 
-    ```bash
-    brew install knative-sandbox/kn-plugins/quickstart
-    ```
+    - Install the `quickstart` plugin by using [Homebrew](https://brew.sh){target=_blank}:
 
+        ```bash
+        brew install knative-sandbox/kn-plugins/quickstart
+        ```
+
+    - Upgrade an existing install to the latest version by running the command:
+
+        ```bash
+        brew upgrade knative-sandbox/kn-plugins/quickstart
+        ```
 === "Using a binary"
     1. Download the executable binary for your system from the [`quickstart` release page](https://github.com/knative-sandbox/kn-plugin-quickstart/releases){target=_blank}.
 

docs/snippets/install-kn.md

@@ -3,14 +3,18 @@ The Knative CLI (`kn`) provides a quick and easy interface for creating Knative
 The `kn` CLI also simplifies completion of otherwise complex procedures such as autoscaling and traffic splitting.
 
 === "Using Homebrew"
-    For macOS, you can install `kn` by using [Homebrew](https://brew.sh){target=_blank}:
 
-    ```bash
-    brew install kn
-    ```
+    - Install `kn` by using [Homebrew](https://brew.sh){target=_blank}:
 
-    !!! note
-        The `quickstart` plugin requires `kn` v0.25 or later. To upgrade an existing install to the latest version, run `brew upgrade kn`.
+        ```bash
+        brew install kn
+        ```
+
+    - Upgrade an existing install to the latest version by running the command:
+
+        ```bash
+        brew upgrade kn
+        ```
 
     ??? bug "Having issues upgrading `kn` using Homebrew?"