Add rustfmt.toml

This adds a rustfmt configuration with project formatting options.

Change-Id: I9fb8c3ee387b0be3296189723cb20f7cbec2153f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/qg/+/119291
Reviewed-by: Erik Gilling <konkers@google.com>
diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 0000000..389a648
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,3 @@
+edition = "2021"
+normalize_comments = true
+use_field_init_shorthand = true