Change "scheme" to "schema"

Apparently I misread the GraphQL docs...

schema/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "schema"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+cynic = "3.2"
+
+[build-dependencies]
+cynic-codegen = "3.2"

schema/src/lib.rs

@@ -0,0 +1,14 @@
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}