editorconfig: added basic config

.editorconfig

@@ -0,0 +1,13 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 2
+tab_width = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.yml]
+indent_style = space

README.md

@@ -55,3 +55,4 @@ Master always contains latest code, so better use some package manager to vendor
 - Each RTB type should be kept in its own file, named after type
 - File names are in underscore_case, e.g., `type BidRequest` should be declared in `bid_request.go`
 - [go fmt your code](https://blog.golang.org/go-fmt-your-code)
+- [EditorConfig](https://editorconfig.org/) (not required, but useful)