Add quick readme.

software/hexaglobe-watermarking/README.rst

+Watermarking Software Release
+=============================
+
+This Software Release is used by Hexaglobe to deploy their video "watermarking"
+system.
+
+This is basically just an nginx daemon compiled with a few custom modules and with
+a custom configuration, and an "administration" nginx daemon.
+
+This Software Release also supports some early version of the "edge" support
+(i.e you request an instance of hexaglobe-watermarking, with "edge" software-type,
+and this instance will itself request many instances of watermakring over the world, in a
+"computing CDN" style).
+