Delete `examples/riotjs/.editorconfig`

This one is exactly the same as the one in the root directory so there's
no reason for it to be in the riot example folder too.

examples/riotjs/.editorconfig

-root = true
-
-[*]
-indent_style = tab
-end_of_line = lf
-charset = utf-8
-trim_trailing_whitespace = true
-insert_final_newline = true
-
-[package.json]
-indent_style = space
-indent_size = 2
-
-[*.md]
-trim_trailing_whitespace = false