Add some documentation starting points.

docs/add_v6_net.md

@@ -0,0 +1,35 @@
+# `add_v6_net` Command
+
+## Name
+
+	`add_v6_net`
+
+## Synopsis
+
+```
+	add_v6_net ${card} ${vlan} ${group} [{no_ula|isp=abc|no_isp}...] [<IPv6 /64 prefix>]...
+```
+
+## Description
+
+	Adds an internal network segment with the specified vlan on the specified
+card.  The created vlan-adaptor is put into the specified group.  It is setup
+for only IPv6.
+
+	The IPv6 network will make `$(( ${vlan}/10 + ${vlan}%10 ))` into hex digits
+to be appended to the ISP's IPv6 prefix.  This makes it compatible with the
+most common case of `/56` for most ISPs.  If `no_ula` is specified in the
+optional arguments, then a ULA for this network segment will not be created.
+Otherwise, the `${rc_router_network_name}` variable will be hashed and an
+ISP-like prefix of `/48` will be created to which the SLA for the specified
+network will be appended.  The `${rc_router_ula_prefix_size}` can be set to
+`/56` to specify a ULA prefix length of 56.  (No other lengths are supported
+at this time.)
+
+	The `isp=...` flag can be used to assign the specified subnet to be part
+of the `IA_PD` list for the specified ISP.  The `no_isp` flag can be used to
+skip provisioning the specified network with any ISP's DHCPv6 `IA_PD` request.
+
+	Any desired explicit `/64` static prefixes can be configured on this network
+segment, after all other options.  The router will provision itself as `...::1`
+on those prefixes.