[Marketing] Wiki-arcticle to collect Logos from OSGeo projects available

Hi list,

I created a wiki-article where logos of the numerous OSGeo projects can be linked.

The reason for creating the page: last week I wasted hours to get logos of most of the OSGeo projects in printquality to arrange them on a poster for the Linxtag in Berlin. All OSGeo projects: please put links to logos of your project on this page to make it easy to get them for any PR!