docs(swarm local address): add documentation spec for swarm.localAddrs (ipfs#477)

closes ipfs#296

License: MIT
Signed-off-by: Prabhakar-Poudel <[email protected]>

Author: Prabhakar Poudel

SPEC/SWARM.md

@@ -3,9 +3,10 @@
 * [swarm.addrs](#swarmaddrs)
 * [swarm.connect](#swarmconnect)
 * [swarm.disconnect](#swarmdisconnect)
+* [swarm.localAddrs](#swarmlocaladdrs)
 * [swarm.peers](#swarmpeers)
-* [swarm.filters.add](#swarmfiltersadd)
-* [swarm.filters.rm](#swarmfiltersrm)
+* [swarm.filters.add](#swarmfiltersadd) (not implemented yet)
+* [swarm.filters.rm](#swarmfiltersrm) (not implemented yet)
 
 #### `swarm.addrs`
 
@@ -75,6 +76,29 @@ ipfs.swarm.disconnect(addr, function (err) {})
 
 A great source of [examples][] can be found in the tests for this API.
 
+#### `swarm.localAddrs`
+
+> Local addresses this node is listening on.
+
+##### `ipfs.swarm.localAddrs([callback])`
+
+`callback` must follow `function (err, multiAddrs) {}` signature, where `err` is an error if the operation was not successful. `multiAddrs` will be an array of [`MultiAddr`](https://github.com/multiformats/js-multiaddr).
+
+If no `callback` is passed, a promise is returned.
+
+**Example:**
+
+```JavaScript
+ipfs.swarm.localAddrs(function (err, multiAddrs) {
+  if (err) {
+    throw err
+  }
+  console.log(multiAddrs)
+})
+```
+
+A great source of [examples][] can be found in the tests for this API.
+
 #### `swarm.peers`
 
 > List out the peers that we have connections with.