Add note to README about dynamic hostname info

The `vagrant-hosts` plugin currently does not pull information from dynamic
sources such as DHCP network interfaces or provider-specific SSH info.

Ref #45

README.markdown

@@ -8,6 +8,9 @@ Manage vagrant guest local DNS resolution.
 Synopsis
 ========
 
+The `vagrant-hosts` plugin provides a `hosts` provisioner which assembles hosts file content based on explicit information and `private_network` settings. Dynamic sources of hostname info, such as DHCP or provider-specific SSH info are currently not considered.
+
+
 Provisioner Settings
 --------------------