Addons docs

doc/user/reference/addons/arctic-dem-addon-data.md

@@ -0,0 +1,19 @@
+# ArcticDEM add-on data
+
+[The Polar Geospatial Center](https://www.pgc.umn.edu/) provides a [custom
+Greenland 32-meter resolution
+ArcticDEM](https://data.pgc.umn.edu/gis/packages/qgreenland/packages/addons/)
+for users of QGreenland.
+
+Two download packages are provided for the v4.1 ArcitcDEM:
+
+* `arcticdem_v4.1_32m_greenland_dem_only.zip`: A ~4.1GB package containing only
+  the 32-m resolution DEM.
+
+* `arcticdem_v4.1_32m_greenland_dem_full.zip`: A ~9.5GB package containing the
+  32-m resolution DEM and ancillary datasets (e.g., a "count" dataset giving the
+  number of contributing DEMs for each pixel).
+
+Download one of these add-on packages and place it in a suitable location in your
+filesystem. Unzip the package and then follow the directions in the `README.txt`
+file included.

doc/user/reference/addons/index.rst

@@ -0,0 +1,12 @@
+.. _addon-reference:
+
+
+===========
+Add-on data
+===========
+
+.. toctree::
+    :maxdepth: 1
+    :glob:
+
+    ./*

doc/user/reference/index.rst

@@ -15,3 +15,11 @@ Reference
     :glob:
 
     ./*
+
+
+.. toctree::
+    :name: Add-ons
+    :caption: Add-ons
+    :hidden:
+
+    addons/index