Expand summary and rename feature to account for expanded scope

text/0000-ipv6addr-octets.md

@@ -1,13 +1,13 @@
-- Feature Name: ipv6addr_octets_interface
+- Feature Name: ipaddr_octet_arrays
 - Start Date: 2016-02-12
 - RFC PR: (leave this empty)
 - Rust Issue: (leave this empty)
 
 # Summary
 [summary]: #summary
 
-Add constructor and conversion functions for `std::net::Ipv6Addr` that are
-oriented around octets.
+Add constructor and conversion functions for `std::net::Ipv6Addr` and
+`std::net::Ipv4Addr` that are oriented around arrays of octets.
 
 # Motivation
 [motivation]: #motivation
@@ -56,6 +56,8 @@ impl From<[u8; 4]> for Ipv4Addr {
 }
 ```
 
+Note: `Ipv4Addr` already has an `octets` method that returns a `[u8; 4]`.
+
 # Drawbacks
 [drawbacks]: #drawbacks