US01: Make it possible for the user to add a horse through the API

backend/.editorconfig

@@ -0,0 +1,14 @@
+root = true
+
+[*]
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = false
+charset = utf-8
+indent_style = space
+indent_size = 4
+tab_width = 4
+
+[{*.yml,*.yaml,*.json,*.sql}]
+indent_style=space
+indent_size=2