docs: Update doc.go with latest arguments.

[matthawkins90]

New arguments according to config.go:

• --logsize
• --authtype
• --clientcafile

Also fixed a minor typo in --externalip to match standard formatting.

[matthawkins90]

This might be out of scope of this PR, but I don't really understand what --externalip and --nodiscoverip do.

externalip = "Add an IP to the list of local addresses we claim to listen on to peers"
nodiscoverip = "Disable automatic network address discovery of local external IPs"

How is externalip different from addpeer?

How is nodiscoverip different from nolisten or noseeders?

[davecgh]

Essentially, inbound vs outbound. externalip/nodiscoverip has to do with the IP that you advertise to other peers in order for them to be able to connect inbound to your node, because often nodes are sitting behind NAT, VPNs, etc and therefore the external IP (aka your public IP that is visible to the internet) is not the same as whatever your local IP is (which is often something like 192.168.x.x).

addpeer is for specifying other peers to always maintain an outbound connection to and is most useful for miners and more exotic network setups such as when you have multiple nodes sitting behind a VPN that you want to remain private but still ensure are connected with your exit node so they can stay synced to the network.

nolisten turns off the ability to accept inbound connections via p2p altogether.

noseeders turns off the ability to discover other peers via the https-based seeders. Without those, it only uses whatever addresses have previously been discovered and are stored in the local address manager.

[matthawkins90]

Ok, so when the description for externalip says the list we claim to listen to, who is "we"? Is it the Decred Seeders?

Can we change that description to something more clear, something like:
externalip = "Add an IP to the list of local addresses that dcrd will advertise to other peers (default: your external WAN IP)"

nodiscoverip = "Disable automatic network address discovery of local external IPs which will be broadcast to other peers"

I'm not even sure my suggestions are more clear, but I think both descriptions could use some improvement.

[davecgh]

"we" is us, as in the local node. I don't mind the updated descriptions, except the default probably shouldn't be there because the real value is not available at the point the help is run.