DEVDOCS-6145: [update] replace nvm 18.15.0 with 20.16.0 (#631)

<!-- Ticket number or summary of work -->
# [DEVDOCS-6145]


## What changed?
Update with the new nvm version

## Release notes draft

Updated the required node and npm versions for installing Stencil CLI.

<!-- Provide an entry for the release notes using simple, conversational
language. Don't be too technical. Explain how the change will benefit
the merchant and link to the feature.

Examples:
* The newly-released [X feature] is now available to use. Now, you’ll be
able to [perform Y action].
* We're happy to announce [X feature], which can help you [perform Y
action].
* [X feature] helps you to create [Y response] using the [Z query
parameter]. Now, you can deliver [ex, localized shopping experiences for
your customers].
* Fixed a bug in the [X endpoint]. Now the [Y field] will appear when
you click [Z option]. -->
* 

## Anything else?
<!-- Add related PRs, salient notes, additional ticket numbers, etc. -->

ping {names}


[DEVDOCS-6145]:
https://bigcommercecloud.atlassian.net/browse/DEVDOCS-6145?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

docs/storefront/stencil/cli/install.mdx

@@ -28,10 +28,10 @@ arch -x86_64 /bin/zsh
 curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.31.0/install.sh | bash
 
 # Install Stencil CLI supported version of Node.js
-nvm install 18.15.0
+nvm install 20.16.0
 
 # Switch to Stencil CLI supported version of Node.js:
-nvm use 18.15.0
+nvm use 20.16.0
 
 # Install Stencil CLI
 npm install -g @bigcommerce/stencil-cli
@@ -54,10 +54,10 @@ Run the following commands:
 
 ```shell showLineNumbers copy
 # Install Stencil CLI supported version of Node.js
-nvm install 18.15.0
+nvm install 20.16.0
 
 # Switch to Stencil CLI supported version of Node.js
-nvm use 18.15.0
+nvm use 20.16.0
 
 # Install Stencil CLI
 npm install -g @bigcommerce/stencil-cli
@@ -81,7 +81,7 @@ choco install git
 
 # Install nvm windows and stencil-compatible node.js
 
-choco install nvm; nvm install 18.15.0; nvm use 18.15.0
+choco install nvm; nvm install 20.16.0; nvm use 20.16.0
 
 # Install Stencil CLI
 npm install -g @bigcommerce/stencil-cli
@@ -103,7 +103,7 @@ If you're a pro at installing and configuring Python and Node.js environments on
 
 **Required Dependencies:**
 * [Git](https://git-scm.com/downloads) - required to run npm install
-* [Node.js 18.15.0 and npm](https://nodejs.org/en/download/releases/) 
+* [Node.js 20.16.0 and npm](https://nodejs.org/en/download/releases/) 
 
 Once they're installed and configured, use `npm` to install Stencil CLI:
 
@@ -128,9 +128,9 @@ curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.36.0/install.sh | bash
 source ~/.bashrc
 
 # Explicitly install and use supported node version
-nvm install 18.15.0
+nvm install 20.16.0
 
-nvm use 18.15.0
+nvm use 20.16.0
 
 # Install stencil
 npm install -g @bigcommerce/stencil-cli