Define R-Spatial

Seem reasonable @edzer, @rsbivand and @rspatial?

Author: Robinlovelace

osgeo-email.md

@@ -17,6 +17,8 @@ After a discussion on our GitHub Organisation at [github.com/r-spatial](https://
 
 Continued development and innovation in R-OSGeo links are illustrated the [qgisprocess](https://github.com/paleolimbot/qgisprocess) package, which motivated positive changes in the QGIS source code (see [github.com/paleolimbot/qgisprocess/issues/21](https://github.com/paleolimbot/qgisprocess/issues/21)). The R-Spatial community relies on the OSGeo projects GDAL, PROJ and GEOS for data access and geographic operations. Core R-Spatial packages `sf`, `raster` and `terra` use bindings to the libraries for much of the heavy lifting and many thousands of people using R for spatial research (often without knowing) run OSGeo support code every day. We would like to support the ongoing work of these vital components of the wider community that is represented by the OSGeo-affiliated conference series FOSS4G. We also anticipate benefits from being part of the wider OSGeo community and would like to be more active members of wider movement advocating free and open source software for geospatial.
 
+'R-Spatial' is can be loosely defined as the ecosystem of code, projects and people using R for working with and adding value to spatial data. A manifestation of the wider R-Spatial community is the friendly, vibrant and diverse range of voices using the [#rspatial](https://twitter.com/search?q=%23rspatial) tag on Twitter. For the purposes of OSGeo supported *software* projects however, we define R-Spatial packages as those that can be found on at https://github.com/rspatial/ (which includes key packages `raster` and `terra`) and https://github.com/r-spatial/ (which includes `sf`, `stars` and many other popular packages for working with spatial data).
+
 Specifically, we would like to initiate the three-step process need to become a full OSGeo project, as outlined on the [Incubation Committee web page](https://wiki.osgeo.org/wiki/Incubation_Committee#Step_1:_Add_OSGeo_Website_Project_Page):
 
 - We would like to create an OSGeo web page with information about key packages in the 'R-spatial stack', including how they relate to OSGeo projects