Translate README to Spanish

[paolacernada]

Title

Translate README to Spanish

Description

Is your feature request related to a problem? Please describe.
The current README file for EasyMDE is only available in English. This limits accessibility for Spanish-speaking users who may find it challenging to understand the documentation and usage instructions.

Describe the solution you'd like
Translate the entire README file into Spanish and add a link at the top of the README for users to switch to the Spanish version. This will make EasyMDE more accessible and user-friendly for Spanish-speaking users.

Describe alternatives you've considered
An alternative solution would be to create a separate repository for translations, but this may lead to confusion and maintenance challenges.

This enhancement will help broaden the user base and improve usability for non-English speakers.

Additional context
Here is a mock-up of how the README could include a language switcher at the top:

# EasyMDE - Markdown Editor

[![English](https://img.shields.io/badge/lang-English-blue.svg)](README.md) [![Spanish](https://img.shields.io/badge/lang-Spanish-red.svg)](README.es.md)