LSPS2 opens channels that are insufficient to pay initial invoice with `channel_over_provisioning_ppm: 0`

[TheBlueMatt]

Kinda obvious, but should at least be documented - it'll open a channel and then not be able to pay because of reserve (or msat rounding).

[tnull]

Yeah, this is basically #478: we'll be looking to generally rework/improve all the parameters and the initial API design, hopefully based on some user feedback.