add animated gif

Author: smathermather

source/arguments_edit/align.rst

@@ -1,3 +1,9 @@
 Uses `CODEM <https://github.com/NCALM-UH/CODEM>`_, credits to Craig Glennie and the group at CRREL.
 
 The details of the method are available at https://github.com/NCALM-UH/CODEM/blob/main/docs/details.md.
+
+.. figure:: images/align_pc.gif
+   :alt: Animated gif comparing two separately processed, but aligned digital surface models.
+   :align: center
+
+Animated gif comparing two separately processed, but aligned digital surface models.