Add notes for Sonoff 4CH updates (ensure to copy out timespec.chan*; remove 1MB build

README.md

@@ -35,11 +35,32 @@ build_vars:
 Note: OTA will not work on these devices, for lack of flash space for the
 alternate boot partition.
 
+When updating these, ensure you have a copy of the timespec files:
+
+```
+mos get timespec.chan0
+mos get timespec.chan1
+mos get timespec.chan2
+mos get timespec.chan3
+```
+
+After flashing, but them back:
+
+```
+mos put timespec.chan0
+mos put timespec.chan1
+mos put timespec.chan2
+mos put timespec.chan3
+```
+
 ### Using Sonoff-4CH
 
+Don't forget to copy the timespec files!
+
 Sonoff 4CH uses a bunch of GPIO pins for the LEDs and pushbuttons, and as such
 has no space for sensors.
 
 ```
 mos config-set app.config=sonoff-4ch.json sensors.dht_gpio=""
 ```
+