docs(chips-api/analog): add signal generator, scope and RC filter examples (#215)

- [R-C filter](https://wokwi.com/projects/409325290405496833) -- Simulates a low-pass R-C filter with 1 analog input, one analog output, and 4 attributes.
- [Signal generator and Scope](https://wokwi.com/projects/359331973918199809) -- Simulates a signal generator with 5 attribute inputs and 1 analog output, and a scope with 4 digital inputs, 4 analog inputs and 4 attribute inputs.  Chip code for both in Wokwi tabs. ([Scope github](https://github.com/Dlloydev/Wokwi-Chip-Scope))

Author: drf5n

docs/chips-api/analog.md

@@ -19,3 +19,5 @@ This method can be called before setting the pin to `ANALOG` mode, but the volta
 
 - [Analog API chip example](https://wokwi.com/projects/330112801381024338) -- Simulates a 0-5V/0-ADC_MAX voltage source. One float attribute and one analog output.
 - [Dual Op-Amp chip example](https://wokwi.com/projects/409320061010147329) -- Simulates a dual Op-Amp with 4 analog inputs, 2 analog outputs, 2 float attributes.
+- [R-C filter](https://wokwi.com/projects/409325290405496833) -- Simulates a low-pass R-C filter with 1 analog input, one analog output, and 4 attributes.
+- [Signal generator and Scope](https://wokwi.com/projects/359331973918199809) -- Simulates a signal generator with 5 attribute inputs and 1 analog output, and a scope with 4 digital inputs, 4 analog inputs and 4 attribute inputs.  Chip code for both in Wokwi tabs. ([Scope github](https://github.com/Dlloydev/Wokwi-Chip-Scope))