Update SVGs with the latest icon pack

#295

Author: khalidabuhakmeh

src/content/docs/identityserver/overview/images/application-architecture.svg

@@ -134,7 +134,7 @@ One of the primary use cases of the token exchange specification is creating tok
 impersonation scenarios. In these scenarios you want to forward certain token and identity information over multiple
 hops in a call chain.
 
-![A digrams showing how token exchange works](images/token_exchange.png)
+![A digrams showing how token exchange works](images/token_exchange.svg)
 
 ## Impersonation
 

src/content/docs/identityserver/overview/images/middleware.svg

@@ -18,7 +18,7 @@ back to the client.
 The consumer of the token must use the [introspection](/identityserver/reference/endpoints/introspection.md) endpoint to
 validate the token.
 
-![reference tokens diagram](images/reference_tokens.png)
+![reference tokens diagram](images/reference_tokens.svg)
 
 You can set the client's token type using the following client setting: