Merge branch 'L2SS-905-2-subrack-instructions' into 'master'

L2SS-905 added readm with instructions on how to support 2 subracks

Closes L2SS-905

See merge request !429

CDB/stations/README.md

+## adding support for 2 subracks
+These are the required changes that need to be made in order to support multiple subracks.
+
+
+
+##### In the config file:
+
+	- add all the new devices under the "STAT/DEVICE/2" name with the correct IP addresses, ports and other properties. This includes: APSCT, APSPU, RECV and UNB2.
+	- Put the new devices in the "Device_Names" list for the boot devices
+	- Set the first 8 bools in "STAT/SDP/1" ... "TR_fpga_mask_RW_default" to True (instead of the first 4 with 1 subrack). This enables the new FPGA's
+	
+	
+
+
+##### In the jupyter startup script
+
+	- Change all "STAT/DEVICE/1" device variable names to end with "_1"
+	- Add all new "STAT/DEVICE/2" devices with their names ending in "_2"
+	- update the devices list with the new devices and changed names
+