docs(@emabrk/site): add docs for dappConnection

site/source/docs/environments.md

@@ -17,11 +17,6 @@ Let's take a look at the `config/contracts.js` file that we've created in the [Q
 ```
 module.exports = {
   default: {
-    deployment: {
-      host: "localhost",
-      port: 8546,
-      type: "ws"
-    },
     dappConnection: [
       "$WEB3",
       "ws://localhost:8546",
@@ -37,7 +32,7 @@ module.exports = {
 }
 ```
 
-Don't get too overwhelmed by all the different options and what they mean. We'll discuss those in-depth in [configuring Smart Contracts](contracts_configuration.html). The important part here is that `contracts.js` exports an object that provides a `default` configuration. This configuration is the default environment and can be overwritten or extended by other environments. 
+Don't get too overwhelmed by all the different options and what they mean. We'll discuss those in-depth in [configuring Smart Contracts](contracts_configuration.html) and `dappConneciton` [here](/docs/javascript_usage.html#Using-dappConnection). The important part here is that `contracts.js` exports an object that provides a `default` configuration. This configuration is the default environment and can be overwritten or extended by other environments. 
 
 If we execute `$ embark run`, Embark will use the `default` configuration to deploy our application's Smart Contracts.
 

site/source/docs/installing_embarkjs.md

@@ -18,8 +18,8 @@ Let's see what that generated config file looks like at `embarkArtifacts/config/
 {
   "dappConnection": [
     "$WEB3",
-    "ws://localhost:8546",
-    "http://localhost:8545"
+    "$EMBARK",
+    "ws://localhost:8546"
   ],
   "dappAutoEnable": true,
   "warnIfMetamask": true,
@@ -30,7 +30,7 @@ Let's see what that generated config file looks like at `embarkArtifacts/config/
 
 #### Connection parameters:
 
-- **dappConnection**: Copied from the contracts config. This is the list of connections Embark will try to connect to in order.
+- **dappConnection**: Copied from the contracts config. This is the list of connections Embark will try to connect to in order. For more information, look at [the guide on EmbakJS](/docs/javascript_usage.html#Using-dappConnection).
 - **dappAutoEnable**: Copied from the contracts config. This tells EmbarkJS to either automatically connect to Metamask (or Mist) or wait for the developper (you) to do it.
  - Read more on it [below](#Provider)
 - **warnIfMetamask**: Is true when `isDev` is true in the blockchain config. Will warn you in the console if Metamask is detected, to make sure you connect Metamask correctly to the local node.

site/source/docs/javascript_usage.md

@@ -43,6 +43,30 @@ EmbarkJS.onReady((error) => {
 });
 ```
 
+## Using `dappConnection`
+
+After reading the section above on `EmbarkJS.onReady`, you might be wondering, but where does EmbarkJS connect?
+
+The answer is: you decide! You can configure it using `dappConnection`, a config property you can find in the Contracts config (by default at `config/contracts.js`).
+
+You will notice that property name reused in some other config files too, like the Storage one, because you can configure where those connect too.
+
+`dappConnection` is a bit weird, but is quite simple. It's an array of strings where EmbarkJS will try each of those in order (from 0 to N) and as soon as one of the connections work, it will stop.
+
+In the case of the Contracts config `dappConnection`, the one that is used to connect to the blockchain node and that is indirectly used in `EmbarkJS.onReady`, you will see two special entities: `$WEB3` and `$EMBARK`.
+
+- `$WEB3` tells EmbarkJS to connect to the browser's web3 instance. For example, Metamask or Status.
+- `$EMBARK` tells EmbarkJS to connect to Embark's wallet, implemented using a proxy in between the Dapp and the blockchain node.
+  - This let's you use you own accounts, as set up in your Blockchain config's `accounts` section
+    - If you don't use custom accounts, using `$EMBARK` is still useful, because it connects to the node more easily for you and uses the unlocked accounts on the node, like when using the `dev` `miningMode`
+  - Also, Embark gets to see the transactions processed and logs them back to you in a human readable manner
+  
+If you want, you can also put a valid node URL in the `dappConnection` array. In that case, EmbarkJS will connect directly to the node, without using Embark's proxy.
+It is, however, not recommended as you lose some of Embark's features, like the transaction logger.
+
+If you want to use an external node,  like Infura, we instead recommend to set it in the Blockchain config (`config/blockchain.js`) using the property `endpoint`.
+Then, using `$EMBARK` will use Embark's proxy, which in part will be connected to that endpoint.
+
 ## Requesting account access
 
 As of [EIP1102](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1102.md), decentralized applications MUST request access to a DApp's user accounts. Embark offers several options on how to implement this.