Update .editorconfig to suggest file-scoped namespaces #1202

Author: michaelklishin

.editorconfig

@@ -25,6 +25,9 @@ csharp_indent_case_contents_when_block = true
 csharp_indent_switch_labels = true
 csharp_indent_labels = one_less_than_current
 
+# File-scoped namespaces
+csharp_style_namespace_declarations=file_scoped:suggestion
+
 # Modifier preferences
 csharp_preferred_modifier_order = public,private,protected,internal,static,extern,new,virtual,abstract,sealed,override,readonly,unsafe,volatile,async:suggestion