formatting: remove another data-ogre from the config example

The fix extension will pass the contents on stdin and read the output
from stdout. By invoking `rustfmt` as `rustfmt {rootpath}`, we tell
rustfmt to format the given path and update it on disk. That also
makes rustftm not produce the formatted output to stdout. So the fix
extension ends up writing out empty files.

Differential Revision: https://phab.mercurial-scm.org/D7304

contrib/examples/fix.hgrc

@@ -2,7 +2,7 b''
 clang-format:command = clang-format --style file -i
 clang-format:pattern = (**.c or **.cc or **.h) and not "listfile:contrib/clang-format-ignorelist"
 
-rustfmt:command = rustfmt {rootpath}
+rustfmt:command = rustfmt
 rustfmt:pattern = set:**.rs
 
 black:command = black --config=black.toml -