editorconfig: add

.editorconfig

@@ -0,0 +1,15 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.{yaml,yml}]
+indent_style = space
+
+[.gitlab-ci.yml]
+indent_size = 2