Merge pull request #358 from preactjs/chore/editorconfig

chore: Add editorconfig

Author: rschristian

.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*]
+indent_style = tab
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{*.json,.*rc,*.yml}]
+indent_style = space
+indent_size = 2
+insert_final_newline = false
+
+[*.md]
+trim_trailing_whitespace = false