doc: replace font-awesome icons by translated captions

This removes use of a remote CDN (Cloudflare), as font-awesome is no longer
used.

doc/es/includes/attributes-es.adoc

@@ -0,0 +1,23 @@
+// Spanish translation, courtesy of Eddú Meléndez <eddu.melendez@gmail.com> with updates from Fede Mendez <federicomh@gmail.com>
+:appendix-caption: Apéndice
+:appendix-refsig: {appendix-caption}
+:caution-caption: Precaución
+:chapter-signifier: Capítulo
+:chapter-refsig: {chapter-signifier}
+:example-caption: Ejemplo
+:figure-caption: Figura
+:important-caption: Importante
+:last-update-label: Ultima actualización
+ifdef::listing-caption[:listing-caption: Lista]
+ifdef::manname-title[:manname-title: Nombre]
+:note-caption: Nota
+:part-signifier: Parte
+:part-refsig: {part-signifier}
+ifdef::preface-title[:preface-title: Prefacio]
+:section-refsig: Sección
+:table-caption: Tabla
+:tip-caption: Sugerencia
+:toc-title: Tabla de Contenido
+:untitled-label: Sin título
+:version-label: Versión
+:warning-caption: Aviso