Add serde and toml for parsing the config.

src/config/definition.rs

@@ -1,4 +1,8 @@
+use serde::Deserialize;
+use serde::Serialize;
+
 /// This is the struct for the writer.toml config file that ends up in each site's root directory.
+#[derive(Deserialize, Serialize)]
 pub(crate) struct Config {
     foo: String,
 }