[fineoffsetweatherstation] Fix README.md (#13506)

* fix typo
* link community thread
* add note for derived values

Signed-off-by: Andreas Berger <andreas@berger-freelancer.com>

bundles/org.openhab.binding.fineoffsetweatherstation/README.md

@@ -8,7 +8,7 @@ Some of these brands are e.g.:
 * Ambient Weather
 * Ecowitt
 * ELV
-* Frogitt
+* Froggit
 * Misol
 * Pantech
 * Sainlogic
@@ -21,6 +21,10 @@ Here is a product picture of how this Weather Station looks like:
 
 This binding works offline by [implementing the wire protocol](https://osswww.ecowitt.net/uploads/20210716/WN1900%20GW1000,1100%20WH2680,2650%20telenet%20v1.6.0%20.pdf) of the WiFi gateway device.
 
+## Discussion
+
+If you have any issues or feedback, please feel free to [get in touch via the community forum](https://community.openhab.org/t/fine-offset-weather-station-binding-discussion/134167) 
+
 ## Supported Things
 
 - `weatherstation`: A Fine Offset gateway device with the ThingTypeUID `fineoffsetweatherstation:weatherstation` which supports the [wire protocol](https://osswww.ecowitt.net/uploads/20220407/WN1900%20GW1000,1100%20WH2680,2650%20telenet%20v1.6.4.pdf) e.g.:
@@ -273,6 +277,9 @@ Valid sensors:
 | piezo-rain-month                      | Number:Length                 | R          | Piezo - Rainfall this Month                    |
 | piezo-rain-year                       | Number:Length                 | R          | Piezo - Rainfall this Year                     |
 
+NOTE: Not every gateway provides all available data, even if they are displayed in the WS-View app.
+Especially the channels `temperature-dew-point` or `temperature-wind-chill` are derived from other measured values.
+
 ### `sensor` Channels
 
 | Channel        | Type                     | Read/Write | Description                 |