Update Smart-Meter-Interface.md, add page info for FNN OBIS code document

Author: markusdd

docs/Smart-Meter-Interface.md

@@ -67,7 +67,7 @@ The Smart Meter Interface provides a means to connect many kinds of meters to Ta
 
 There are many different meters that use the same protocol. There are multitudes of variants and use cases. This interface provides a means of specifying these definitions through [meter descriptors](#meter-metrics). This method uses the [scripting language](Scripting-Language) editor to define the descriptors. In this way, only one firmware binary version is required and a modification can be made easily _on the fly_.  
 
-For meters that follow the German 'Basiszähler' standard, which is often referenced in their manuals as "Lastenheft Basiszähler Funktionale Merkmale", the SML OBIS codes for the datapoints can be found in this central [VDE document](https://www.vde.com/resource/blob/2345790/e6c822aa22d51592aba388f6a5ceaed2/fnn-hinweis--lastenheft-basiszaehler---funktionale-merkmale---2018--data.pdf). Please note that not all meters emit all of these datapoints, especially the per-phase information is sometimes omitted. Total consumption, feed and momentary power should always be available though.
+For meters that follow the German 'Basiszähler' standard, which is often referenced in their manuals as "Lastenheft Basiszähler Funktionale Merkmale", the SML OBIS codes for the datapoints can be found in this central [VDE document](https://www.vde.com/resource/blob/2345790/e6c822aa22d51592aba388f6a5ceaed2/fnn-hinweis--lastenheft-basiszaehler---funktionale-merkmale---2018--data.pdf) from page 41 onwards. Please note that not all meters emit all of these datapoints, especially the per-phase information is sometimes omitted. Total consumption, feed and momentary power should always be available though.
 
 !!! note
     Additional hardware may be required to read certain measuring devices. For example: RS485toTTL adapter for Modbus, IR transistor for electricity meters. Sometimes an additional IR diode and resistors.