Add a DOCS.txt file to collect useful docs

diff --git a/DOCS.txt b/DOCS.txt
new file mode 100644 (file)
index 0000000..b29af25
--- /dev/null
+++ b/DOCS.txt
@@ -0,0 +1,2 @@
+GStreamer Plugin Writer's Guide
+http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/pwg.pdf