Merge pull request #32 from morpho-labs/docs/readme

README.md

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 # Morpho Blue Oracles
 
+
+Morpho Blue Oracles are contracts that can be used as oracles for markets on [Morpho Blue](https://github.com/morpho-org/morpho-blue).
+The oracles implement the `IOracle` interface defined in [`IOracle.sol`](https://github.com/morpho-org/morpho-blue/blob/main/src/interfaces/IOracle.sol#L9): they return the price of 1 asset of collateral token quoted in 1 asset of loan token.
+
+## ChainlinkOracle
+
+The `ChainlinkOracle` is an oracle that uses Chainlink-compliant feeds to provide price data.
+
+This oracle handles the following cases among others (let's say that our pair is A/B):
+- A/B is a feed (typically, stETH/ETH).
+- B/A is a feed (typically, ETH/USDC).
+- A/C and B/C are feeds (typically, stETH/ETH and USDC/ETH).
+- A/C, C/D and B/D are feeds (typically, WBTC/BTC, BTC/USD, USDC/USD).
+- A/D, and B/C, C/D are feeds (typically, USDC/USD, WBTC/BTC, BTC/USD).
+- A/C, C/D and B/E, E/D are feeds.
+- A/C and C/B are feeds (typically, WBTC/BTC and BTC/ETH).
+- A'/C and B/C are feeds, and there is an exchange rate between A and A'. (typically A=sDAI and A'=DAI).
+
+## Getting Started
+
+Install dependencies: `forge install`
+
+In a `.env` file, set `ETH_RPC_URL` to the URL of an Ethereum provider.
+
+Run test: `forge test`
+
 ## License
 
 Morpho Blue Oracles are licensed under `GPL-2.0-or-later`, see [`LICENSE`](./LICENSE).