Fix indenting for C#

Fix the indent size for C# code files.

Author: martincostello

.editorconfig

@@ -8,5 +8,8 @@ charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
 
+[*.cs]
+indent_size = 4
+
 [*.md]
 trim_trailing_whitespace = false