Add narrative documentation on how we do binary deployment

Nobody has claimed this yet.

Now that our https://github.com/mapbox/cpp/blob/master/glossary.md is fairly complete, it is a good time to add new, narrative docs that tie together glossary terms.

In particular, there is a need for a binary deployment doc that explains the flow from C++ source code -> node addons -> binary distribution.

Here is a first stab at listing things to cover in this doc:

We use mason for:

- distributing [pre-compiled](https://github.com/mapbox/cpp/blob/master/glossary.md#precompiled) (aka binary) static libraries for C/C++ code. And in rare cases shared libraries.
- distributing source code of header-only libraries
- distributing binaries of [executables](https://github.com/mapbox/cpp/blob/master/glossary.md#executable) (aka command line programs).

We use node-pre-gyp for:

- Binary deployment of node C++ addons
- When those node C++ addons have external C/C++ dependencies we use mason to pull packages for them
- Soon we'll open source https://github.com/mapbox/mason-js which will make these more seamless (no need for the mason bash scripts)

TODO:

- integrate old node-pre-gyp docs into this repo and modify them to link to the glossary and this repo where appropriate. E.g. https://github.com/mapbox/node-pre-gyp/wiki/External-libraries, https://github.com/mapbox/node-pre-gyp/wiki/FAQ

Start with glossary.md and the existing node-pre-gyp wiki pages for External-libraries and FAQ. Trace the documented flow from C++ source through node addons to binary distribution, covering mason and node-pre-gyp, then integrate the relevant old documentation into this repository with links to the glossary and related material.

Written by the indexing model from the issue text.