Document how to build portable, cross-platform binaries

Nadie ha tomado este issue todavía.

Creating C++ binaries portable to a given platform (osx, linux, windows) or platform version (ubuntu precise or trusty) is absolutely feasible but a poorly documented topic. Often our goal at Mapbox is to support the latest C++11 and C++14 features but maintain code portable to older operating systems like Windows 7, OS X 10.8, and Ubuntu Precise, or RHEL 6/7. This is also feasible. For example its possible to run C++14 binaries on AWS lambda (built on ubuntu precise) even though you can't easily compile them on AWS Lambda.

We should document how Mapbox writes and distributes portable C?C++ code to make clear when this approach is advantageous and when it is not. And to ensure the techniques are robust and replicable.

This issue is to track:

- [ ] getting this all documented here
- [ ] Moving the content from https://github.com/mapbox/node-pre-gyp/wiki/External-libraries to this future doc
- [ ] Moving binary portability FAQ from https://github.com/mapbox/node-pre-gyp/wiki/FAQ#frequently-ask-questions-about-node-pre-gyp to here

Comienza revisando la página de wiki „External libraries“ de node-pre-gyp y las preguntas frecuentes sobre portabilidad binaria enlazadas en el issue. Consolida el material relevante en la documentación planificada, explicando cuándo son ventajarios los binarios portables de C/C++ y cómo Mapbox los escribe y distribuye. Se considera terminado cuando el tema esté documentado aquí y ambas fuentes enlazadas hayan sido migradas.

Escrito por el modelo de indexación a partir del texto del issue.