[cosmwasm] add readme to pyth cosmwasm (#520)

* add readme to pyth cosmwasm

* update readme

* update readme

target-chains/cosmwasm/contracts/README.md

@@ -1,3 +1,68 @@
-# Terra Wormhole Contracts
+# Pyth Cosmwasm
 
-The Wormhole Terra integration is developed and maintained by Everstake / @ysavchenko.
+This crate includes the actual contract and exposes utilities to interact with the contract on the CosmWasm ecosystem.
+It also includes an [example contract](../examples/cw-contract/) demonstrating how to read price feeds from on-chain CosmWasm applications.
+
+## Installation
+
+Add this crate to the dependencies section of your CosmWasm contract's `Cargo.toml` file:
+
+```
+[dependencies]
+pyth-cosmwasm = { git="https://github.com/pyth-network/pyth-crosschain", rev="5d0acc1", features=["library"] }
+```
+
+## Usage
+
+Simply import the structs exposed by the crate and use them while interacting with the pyth contract. For example:
+
+```rust
+// to query Pyth contract
+use pyth_cosmwasm::msg::{
+    PriceFeedResponse,
+};
+
+... {
+    let price_feed_response: PriceFeedResponse =
+    deps.querier.query(&QueryRequest::Wasm(WasmQuery::Smart {
+        contract_addr: state.pyth_contract_addr.into_string(),
+        msg:           to_binary(&PythQueryMsg::PriceFeed {
+            id: state.price_feed_id,
+        })?,
+    }))?;
+
+    let price_feed = price_feed_response.price_feed;
+}
+....
+```
+
+## Off-Chain Queries
+
+You can use the provided schemas in the `./pyth/schema` directory to directly query the CosmWasm contract from off-chain applications.
+A typical query requires to pass the price feed id as a hex string. it will look like:
+
+```
+{
+    "price_feed": {
+        "id": "f9c0172ba10dfa4d19088d94f5bf61d3b54d5bd7483a322a982e1373ee8ea31b"
+    }
+}
+```
+
+## Contracts and Price Feeds
+
+Pyth is currently available on the following cosmwasm chains:
+
+### Testnet
+
+| Network   | Contract address                             |
+| --------- | -------------------------------------------- |
+| Injective | `inj1z60tg0tekdzcasenhuuwq3htjcd5slmgf7gpez` |
+
+Available price feeds on these networks can be find below:
+
+### Price Feeds
+
+| Network           | Available Price Feeds                                                                                                                |
+| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
+| Injective Testnet | [https://pyth.network/developers/price-feed-ids#injective-testnet](https://pyth.network/developers/price-feed-ids#injective-testnet) |