Add more information to readme

README.md

@@ -15,11 +15,20 @@ This is a simple .Net Standard 2.0 library supporting ARP lookups on Windows and
 
 This library currently provides one single, simple to use function:
 
-    using ArpLookup;
+```C#
+using System.Net.NetworkInformation;
+using ArpLookup;
 
-    // ...
+// ...
 
-    var mac = await Arp.LookupAsync(IPAddress.Parse("1.2.3.4"));
+PhysicalAddress mac = await Arp.LookupAsync(IPAddress.Parse("1.2.3.4"));
+```
+
+
+Detect if the current platform is supported. Lookups on unsupported plattforms throw `PlatformNotSupportedException`s.
+```C#
+var linuxOrWindows = Arp.IsSupported;
+```
 
 ## Further information
 
@@ -28,6 +37,12 @@ On Windows an API call to IpHlpApi.SendARP is used. Beware that this implementat
 On Linux the `/proc/net/arp` file, which contains system's the arp cache, is read. If the IP address is found there the corresponding MAC address is returned directly.
 Otherwise, an ICMP ping is sent to the given IP address and the arp cache lookup is repeated afterwards. This implementation uses async file IO and the framework's async ping implementation.
 
+Per default, the library waits for ping responses for up to 750ms on linux platforms. Technically, the responses are not required, as the arp protocol and the arp cache have nothing to do with the pings. Rather, the pings are an easy way to force the OS to figure out and provide the information we are looking for. I did not do extensive tests how long is reasonable to wait to be quite sure, the arp cache is updated. 750ms should be much more than needed in many cases - it is more of the safe option. Note that if you do recieve a ping response, the wait might be much shorter. The timeout gets relevant if the host is not available/no ping answer is received. If you want to request many addresses or are facing other time-limiting aspects, you may want to reconfigure this default:
+
+```C#
+Arp.LinuxPingTimeout = TimeSpan.FromMilliseconds(125);
+```
+
 ## Credits
 
 The windows version is based on [nikeee/wake-on-lan](https://github.com/nikeee/wake-on-lan).