point to nfsroot documentation and explain ip parameter

README.md

@@ -12,13 +12,14 @@ website](https://cryptops.com)
 ## VPS setup
 
 Some variables need to be passed to the initrd with kernel options. They are
-retrieved from `/proc/cmdline`.
+retrieved from `/proc/cmdline`. [Here's the official
+documentation.](https://github.com/torvalds/linux/blob/master/Documentation/filesystems/nfs/nfsroot.txt)
 
 - `root=/dev/mapper/xvda1_crypt`: The partition that needs to be mounted as root
 - `cryptroot=/dev/xvda`: The device that needs to be partitioned and encrypted
 - `ip=213.108.110.71::213.108.110.126:255.255.255.128:encrypted-system:eth0:off`
-  IP information (
-  `<ip>:<??>:<gateway>:<subnet mask>:<hostname>:<network interface>:<???>`)
+  IP information:
+  `ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns0-ip>:<dns1-ip>`
 
 ### Startup Notification