try to fix submodule

firmware/lib/Arduino-FOC-drivers/src/comms/serial/README.md

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+
+# Serial communications classes
+
+Serial communications classes for register-based control and telemetry from SimpleFOC.
+
+## SerialASCIITelemetry
+
+:warning: unfinished, untested
+
+Telemetry class that sends telemetry as ASCII on a serial port. Similar to the classic "monitoring" functionality of SimpleFOC, but allows you to configure telemetry based on most of the defined registers.
+
+Usage:
+
+```c++
+
+SerialASCIITelemetry telemetry = SerialASCIITelemetry(); // number of float digits to display
+
+void setup() {
+    ...
+    telemetry.addMotor(&motor);
+    telemetry.setTelemetryRegisters(2, [REG_VELOCITY, REG_VOLTAGE_Q]);
+    telemetry.init();
+    ...
+}
+
+void loop() {
+    motor.move();
+    motor.loopFOC();
+    telemetry.run();
+}
+```
+
+Some options are supported:
+
+```c++
+    telemetry.floatPrecision = 4;       // send floats with 4 decimal places
+    telemetry.min_elapsed_time = 0;     // microseconds between sending telemetry
+    telemetry.downsample = 100;         // send every this many loop iterations
+```
+
+
+
+## SerialBinaryCommander
+
+:warning: unfinished, untested!
+
+Control SimpleFOC via a binary protocol over the serial port. The standard SimpleFOC registers are used.
+
+TODO document the protocol