add warning to conditioning

add warning to:
- Readme
- Example Usage
- Function description

README.md

@@ -99,3 +99,11 @@ In these files you can find some helper functions used by Sensirion's embedded
 drivers. It mostly contains byte order conversions for different variable
 types. These functions are also used by the UART embedded drivers therefore
 they are kept in their own file.
+
+## Conditioning
+
+After each restart of the sensor or when the hotplates have been switched off, the conditioning command must
+be called from idle mode. The conditioning heats the hotplate of the NOx pixel to a different temperature compared
+to the measurement mode enabling a faster switch-on thereafter.
+
+It is recommended to execute the conditioning for 10s, but **10s must not be exceeded** to avoid damage to the sensing material.

sgp41_i2c.h

@@ -52,6 +52,9 @@ extern "C" {
  * different temperature for conditioning. This command returns only the
  * measured raw signal of the VOC pixel SRAW_VOC as 2 bytes (+ 1 CRC byte).
  *
+ * WARNING: To avoid damage to the sensing material the conditioning must not
+ * exceed 10s!
+ *
  * @param default_rh Default conditions for relative humidty.
  *
  * @param default_t Default conditions for temperature.

sgp41_i2c_example_usage.c

@@ -82,6 +82,8 @@ int main(void) {
     uint16_t default_t = 0x6666;
 
     // sgp41 conditioning during 10 seconds before measuring
+    // WARNING: To avoid damage to the sensing material the conditioning must
+    // not exceed 10s!
     for (int i = 0; i < 10; i++) {
         uint16_t sraw_voc;