This example is based on a react truffle box obtained frmo the Truffle website
It's not a complete project but shows just how to setup your truffle.js config to deploy to more than one network For example, there are no contracts under contracts/ here but I assume you have contracts names AssetToken.sol and Crowdsale.sol respectively
The main point of this example is to show the use of the truffle.js config file to deploy to one or more networks, your contracts.
usually the 'development' network is a testrpc server in this example, two servers are setup in the config.
In my case, I used a geth localnet as the 'shareddev' server to use during shared development with other devs Testrpc started to break down when I started to use it with the Mist browser, so I switched to geth
I will post another example on how to run a geth localnet of your own
Contract deployment script examples are in contracts/ and migrations/ folder. Check migrations on how to setup migration. That migration 2_*.js was created using truffle create migration command. Check Truffle doc for full ref.
To deploy to development network just run
truffle migrate --network development
To deploy to the 'shareddev' network, run
truffle migrate --network shareddev
Basically that's all you need to do during development phase. Once ready to migrate contracts to real networks, of course you need to update truffle config file for those networks