Update .editorconfig with new book availability dates

Revised the update date for the code performance and coding standards books from March 28, 2025, to May 1, 2025. The URLs for the books remain unchanged.

Author: RealDotNetDave

.editorconfig

@@ -1,10 +1,9 @@
 ####################################################################################################
 # dotNetDave's (David McCarter) Editor Config - dotNetTips.com
 # Updates to this file are posted quarterly at: https://bit.ly/EditorConfig5
-# Updated March 28, 2025
-# NEW code performance book is available at: https://bit.ly/DotNetCodePerf4
-# NEW coding standards book is available at: https://bit.ly/CodingStandards8
-# Rockin' the Code World with dotNetDave: https://bit.ly/RockinCodeWorldShows
+# Updated May 1, 2025
+# Code performance book is available at: https://bit.ly/DotNetCodePerf4
+# Coding standards book is available at: https://bit.ly/CodingStandards8
 ####################################################################################################
 
 root = true