Update UnrealEngine.gitignore

Edited Unreal Engine gitignore to also ignore "Intermediate" data in the "Plugins" directory, so it ignores deeper nested intermediate data, like with Epic's "Game Features" plugin e.g. "Plugins/GameFeatures/MyGameFeature/Intermediate".

UnrealEngine.gitignore

@@ -68,7 +68,7 @@ Saved/*
 
 # Compiled source files for the engine to use
 Intermediate/*
-Plugins/*/Intermediate/*
+Plugins/**/Intermediate/*
 
 # Cache files for the editor to use
 DerivedDataCache/*