Make it easier to run Guide examples

[arkodg]

What would you like to be added:

Inline install instructions for each implementation in https://gateway-api.sigs.k8s.io/guides/#installing-a-gateway-controller so its easier for the end user to test out the guide https://gateway-api.sigs.k8s.io/guides/ without leaving the website

Why this is needed:

• Reduce drop off rate / Increase Gateway API adoption

[arkodg]

Some options

1. . Tabbed Interface
   Use a tabbed layout to group implementations clearly without clutter.

Example:

{{< tabs "Implementation A" "Implementation B" "Implementation C" ... >}}

{{< tab "Implementation A" >}}
Steps for Implementation A...
{{< /tab >}}

{{< tab "Implementation B" >}}
Steps for Implementation B...
{{< /tab >}}

{{< /tabs >}}

2. Expandable (Accordion) Sections
   Use accordions to reveal step-by-step instructions on demand.

Example:

{{< details title="Implementation A" >}}
Step-by-step instructions here.
{{< /details >}}

{{< details title="Implementation B" >}}
Step-by-step instructions here.
{{< /details >}}

3. Filterable or Select Dropdown (Interactive JavaScript Filter)
   Provide a dropdown menu allowing the user to select their implementation.

Implementation: Custom JS or Docsy shortcodes.
Example (pseudo-code):

<select id="implementation-select">
  <option value="impl-a">Implementation A</option>
  <option value="impl-b">Implementation B</option>
  ...
</select>

<div id="impl-a" class="implementation">Steps A</div>
<div id="impl-b" class="implementation" style="display:none;">Steps B</div>
...

4. Side Menu Anchors (In-Page Navigation)
   Side menu anchors jump users directly to implementation steps further down the page.
   Implementation: Markdown anchors supported by Docsy.
   Example:

## Implementations
- [Implementation A](#impl-a)
- [Implementation B](#impl-b)
...

## Implementation A {#impl-a}
Step-by-step instructions...

## Implementation B {#impl-b}
Step-by-step instructions...