Add Dockerfile to editorconfig

Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

.editorconfig

@@ -5,6 +5,10 @@ charset = utf-8
 insert_final_newline = true
 trim_trailing_whitespace = true
 
+[*.Dockerfile]
+indent_size = 4
+indent_style = space
+
 [*.py]
 indent_size = 4
 indent_style = space