Update 'README.md'

Added example and more explaination of how the macros work.

README.md

@@ -2,19 +2,56 @@
 
 **S**td
 
-
 **I**/o
 
-
 **N**egotiator
 
-
 **G**enerator
 
 ## What is sing meant to be?
 
 This crate is meant to create interfaces between traits in Rust libraries and the command line.
-It does this by providing two macros: …
+It does this by providing two macros: 
+
+- `sing_add_trait`, which acts as an attribute to a trait implementation and gathers the method signatures that are used by `sing_loop!`.
+- `sing_loop!`, which takes a trait object and serialization/deserialization functions as well as some optional parameters. It generates a loop parsing function calls coming from STDIN (or any other `BufRead` stream), evaluating them by calling the appropriate method on the object and returning them on STDOUT (or any other `Write` stream).
+
+## Example usage
+
+```rust
+use serde::{Serialize, Deserialize};
+use sing::{sing_add_trait, sing_loop};
+
+trait FruitTree {
+         fn shake(&self, shakes: u32) -> Vec<Fruit>;
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct Fruit {
+         fruit_type: String,
+}
+
+struct BananaTree;
+
+#[sing_add_trait()]
+impl FruitTree for BananaTree {
+         fn shake(&self, shakes: u32) -> Vec<Fruit>{
+                  let mut out = vec!();
+
+                  for _ in 0..shakes {
+                                out.push(Fruit{fruit_type: String::from("Banana")});
+                  }
+                  
+                  out
+         }
+}
+
+fn main() {
+         let tree = BananaTree {};
+         
+    sing_loop!(tree, [different, ron::to_string, ron::from_str],);
+}
+```
 
 ## Negotiator? Really?