message: [chores] Add an example to the README
diff: An [eDSL](https://wiki.haskell.org/Embedded_domain_specific_language) to write WebAssembly based smart contracts in the Rust programming language.
  +## Example
  +
  +Below is an example using the eDSL demonstrating a simple Flipper smart contract
  +that has a boolean state that can be flipped or returned.
  +
  +```rust
  +contract! {
  + /// Flips its state between `true` and `false`.
  + struct Flipper {
  + /// The current state of our flag.
  + value: storage::Value<bool>,
  + }
  +
  + impl Deploy for Flipper {
  + /// Initializes our state to `false` upon deploying our smart contract.
  + fn deploy(&mut self) {
  + self.value.set(false)
  + }
  + }
  +
  + impl Flipper {
  + /// Flips the current state of our smart contract.
  + pub(external) fn flip(&mut self) {
  + if *self.value {
  + *self.value = false
  + } else {
  + *self.value = true
  + }
  + }
  +
  + /// Returns the current state.
  + pub(external) fn get(&self) -> bool {
  + *self.value
  + }
  + }
  +}
  +```
  +
  ## Goals
  ### Core Goals
  