es] Add Spanish translation for kubectl quick-reference page

**This is a Feature Request**

### What would you like to be added

The kubectl quick-reference page (/docs/reference/kubectl/quick-reference/) has no Spanish translation. Spanish is one of the most widely spoken languages globally, making this a high-value missing page. Users browsing Kubernetes docs in Spanish find no kubectl reference page, and the language switcher shows Spanish as greyed out on all other locale versions of this page.

### Proposed solution:
Create content/es/docs/reference/kubectl/quick-reference.md as a Spanish translation of content/en/docs/reference/kubectl/quick-reference.md with the following front matter:

```
---
title: Referencia Rápida de kubectl
translationKey: kubectl-quick-reference
content_type: concept
weight: 10
card:
name: tasks
weight: 10
---
```