update png links in PSY

docs/src/models.md

@@ -65,7 +65,7 @@ The implementation of Synchronous generators as components uses the following st
 share values across components.
 
 ```@raw html
-<img src="https://github.com/nrel-sienna/PowerSystems.jl/blob/master/docs/src/assets/gen_metamodel.png?raw=true" width="75%">
+<img src="https://raw.githubusercontent.com/nrel-sienna/PowerSystems.jl/main/docs/src/assets/gen_metamodel.png" width="75%">
 ```
 
 ## Inverter Models
@@ -84,7 +84,7 @@ components in a way that resembles current practices for synchronoues machine mo
 The following figure summarizes the components of a inverter and which variables they share:
 
 ```@raw html
-<img src="https://github.com/nrel-sienna/PowerSystems.jl/blob/master/docs/src/assets/inv_metamodel.png?raw=true" width="75%">
+<img src="https://raw.githubusercontent.com/nrel-sienna/PowerSystems.jl/main/docs/src/assets/inv_metamodel.png" width="75%">
 ```
 
 Contrary to the generator, there are many control structures that can be used to model