Update README.md

Author: dlmcpaul

README.md

@@ -95,6 +95,6 @@ I may look to document these or try to make them configurable.
 
 There are mechanisms to update the ledger file (accepting a schedule, posting a new journal) but you can primarily use it for visualisation.
 
-![Screenshot](/docs/images/MyMoney-Dashboard.png)
+![Screenshot](/docs/images/MyMoney-Dashboard.PNG)
 
-![Screenshot](/docs/images/MyMoney-Accounts.png)
+![Screenshot](/docs/images/MyMoney-Accounts.PNG)