package/mender: adding a readme file

This patch adds a readme file with basic instructions to get mender up
and running on a production system.

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Acked-by: <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mender/readme.txt

@@ -0,0 +1,18 @@
+=== Notes on using Mender on Buildroot
+======================================
+Default configurations files
+----------------------------
+
+Buildroot comes with a default artifact_info and device_type configuration files
+in /etc/mender. They contain default values, and thus they should be overridden
+on a production system.
+
+The simplest way to do it is to change these files in an overlay or in a post
+build script.
+
+Configuring mender with certificates
+------------------------------------
+
+Mender uses TLS to communicate with the management server, and if you use a
+CA-signed certificate on the server, you should select the ca-certificates
+package otherwise it doesn't work.