dev: Add improved README (#276)

* Add improved README

* Update with more current hub link

packages/contracts/README.md

-# Optimism's Contracts (V2)
+# Optimistic Ethereum Smart Contracts
 
-This package contains the various Ethereum smart contracts that make up the Layer 1 component of Optimism's Optimistic Rollup construction.
+`@eth-optimism/contracts` contains the various Solidity smart contracts used within the Optimistic Ethereum system.
+Some of these contracts are deployed on Ethereum ("Layer 1"), while others are meant to be deployed to Optimistic Ethereum ("Layer 2").
 
-## Building and Running
+Within each contract file you'll find a comment that lists:
+1. The compiler with which a contract is intended to be compiled, `solc` or `optimistic-solc`.
+2. The network upon to which the contract will be deployed, `OVM` or `EVM`.
 
-This package requires that `yarn` be installed on your machine!  Once it is, run `yarn test` to build and run tests.
+A more detailed overview of these contracts can be found on the [community hub](http://community.optimism.io/docs/protocol/protocol.html#system-overview).
 
-## Security
+<!-- TODO: Add link to final contract docs here when finished. -->
+
+## Usage (npm)
+If your development stack is based on Node/npm:
+
+```shell
+npm install @eth-optimism/contracts
+```
+
+Within your contracts:
+
+```solidity
+import { SomeContract } from "@eth-optimism/contracts/SomeContract.sol";
+```
+
+## Guide for Developers
+### Setup
+Install the following:
+- [`Node.js` (14+)](https://nodejs.org/en/)
+- [`npm`](https://www.npmjs.com/get-npm)
+- [`yarn`](https://classic.yarnpkg.com/en/docs/install/)
+
+Clone the repo:
+
+```shell
+git clone https://github.com/ethereum-optimism/contracts.git
+cd contracts
+```
 
-See our [Security Policy](https://github.com/ethereum-optimism/.github/security/policy).
\ No newline at end of file
+Install `npm` packages:
+```shell
+yarn install
+```
+
+### Running Tests
+Tests are executed via `yarn`:
+```shell
+yarn test
+```
+
+Run specific tests by giving a path to the file you want to run:
+```shell
+yarn test ./test/path/to/my/test.spec.ts
+```
+
+### Compiling and Building
+Easiest way is to run the primary build script:
+```shell
+yarn build
+```
+
+Running the full build command will perform the following actions:
+1. `build:contracts` - Compile all Solidity contracts with both the EVM and OVM compilers.
+2. `build:typescript` - Builds the typescript files that are used to export utilities into js.
+3. `build:copy` - Copies various other files into the build folder.
+4. `build:dump` - Generates a genesis state from the contracts that L2 geth will use.
+5. `build:typechain` - Generates [TypeChain](https://github.com/ethereum-ts/TypeChain) artifacts.
+
+You can also build specific components as follows:
+```shell
+yarn build:contracts
+```
+
+## Security
+Please refer to our [Security Policy](https://github.com/ethereum-optimism/.github/security/policy) for information about how to disclose security issues with this code.