[Marketing] Style Guide

[Jeffrey Johnson]

 The most current version of the style guide has been published here.

https://github.com/OSGeo/osgeo/blob/master/marketing/branding/styleguide-osgeo.pdf

Please use issues in this repo to provide feedback.

We need to come up with a plan to convert this to an online version
that can be managed with pull requests. Similar to
https://github.com/GFDRR/innovation-lab-brand-guidelines and the
published version here
http://gfdrr.github.io/innovation-lab-brand-guidelines/ ... It would
be great if we could get a volunteer to help with this process.

Jeff