Nueva documentación - API de Mercado Pago

[pamalv7]

Description

Nueva documentación de la integración por API de Mercado Pago.

Checklist:

Before sending your contribution, please specify the following:

• This request modifies code snippets.
• The contribution aligns with the information stated in the repository wiki.

• Contribution incorporates an article not included until now, which must be added to indexes as a new section.
• Contribution includes new features.
• New features were communicated in changelog.
• Requires translations.