docs: add relevant info to README

Author: MerlinEgalite

README.md

@@ -1,5 +1,30 @@
 # Morpho Blue Oracles
 
+[Morpho Blue](https://github.com/morpho-org/morpho-blue) is a trustless lending primitive that offers unparalleled efficiency and flexibility.
+
+Morpho Blue Oracles are contracts that can be used as oracles for markets on Morpho Blue.
+The oracles must implement the `IOracle` interface defined in [`IOracle.sol`](https://github.com/morpho-org/morpho-blue/blob/main/src/interfaces/IOracle.sol#L9).
+
+## 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, USDC/ETH).
+- 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`
+
+Run test: `forge test`
+
 ## License
 
 Morpho Blue Oracles are licensed under `GPL-2.0-or-later`, see [`LICENSE`](./LICENSE).