add static fields rule

.editorconfig

@@ -13,17 +13,31 @@ trim_trailing_whitespace = true
 charset = utf-8
 max_line_length = 150
 
-# Interfaces should start with I and PascalCase
+## Interfaces should start with I and PascalCase
 # naming style
-dotnet_naming_style.prefix_and_pascal_case.required_prefix = O
+dotnet_naming_style.prefix_and_pascal_case.required_prefix = I
 dotnet_naming_style.prefix_and_pascal_case.capitalization = pascal_case
 
 # naming symbols
 dotnet_naming_symbols.interfaces.applicable_kinds = interface
 
-dotnet_naming_rule.interfaces_begin_with.severity = error
-dotnet_naming_rule.interfaces_begin_with.symbols = interfaces
-dotnet_naming_rule.interfaces_begin_with.style = prefix_and_pascal_case
+dotnet_naming_rule.interfaces_begin_with_I.severity = error
+dotnet_naming_rule.interfaces_begin_with_I.symbols = interfaces
+dotnet_naming_rule.interfaces_begin_with_I.style = prefix_and_pascal_case
 
-dotnet_diagnostic.interfaces_begin_with.enabled = true
+dotnet_diagnostic.interfaces_begin_with_I.enabled = true
 
+## Static fields should start with _s
+# naming style
+dotnet_naming_rule.static_fields_begin_with_s.style = custom
+dotnet_naming_rule.static_fields_begin_with_s.required_prefix = _r
+dotnet_naming_rule.static_fields_begin_with_s.capitalization = camel_case
+
+# naming symbols
+dotnet_naming_symbols.static_fields.applicable_kinds = field
+dotnet_naming_symbols.static_fields.applicable_accessibilities = public, internal, private, protected, protected_internal
+dotnet_naming_symbols.static_fields.required_modifiers = static
+
+dotnet_naming_rule.static_fields_begin_with_s.severity = error
+dotnet_naming_rule.static_fields_begin_with_s.symbols = static_fields
+dotnet_diagnostic.static_fields_begin_with_s.enabled = true