A page before the map, and two ways to stop playing

Diplomacy has a reputation and about half of it is wrong, so the landing
page states the rules completely -- they are short enough -- and says the
strange part out loud: there is no luck in this game, every unit is exactly
as strong as every other, and nothing happens on the board that somebody did
not agree to help with. It is also the honest place for the licence and for
where the map came from. A page that says nothing about that is a page
quietly hoping nobody asks.

The dice on starting are the only joke in here. There are none in this game;
that is the sound of every other board game you have played, and the last
one you hear before finding out that none of this is luck.

Giving up is two different things and concede.ts keeps them apart.

Resigning is unilateral, because nobody is entitled to your attention. But
the power does not leave the board -- it goes into civil disorder, holds
everything, waives its builds and is paid off as it loses centres, which is
what the rules already say happens to an absent player. That matters to
everyone else: a resigned Austria is still eleven centres somebody has to go
and take, and letting them evaporate would hand the game to whoever happened
to be next door. Verified by playing four years past a resignation: Austria
sits on its three while France reaches six.

A draw is not unilateral, and that is what keeps it Diplomacy rather than a
menu. Every surviving power votes, one refusal is enough, and each refusal
comes back with its reason so it can be argued with next year. A power
refuses while it leads or is within two of leading. Asked in Spring 1901 all
six refuse -- the right answer, since a game that could be drawn on the
first turn would not be worth playing.

Conceding is harder to get than a draw and should be: it carries only when
the solo was coming anyway. Otherwise refusing costs nothing but time, and
time is all the losing side has.

The resign button asks twice, in the page rather than in a browser dialog.
It is the one control here that cannot be taken back.

README.md

@@ -333,6 +333,51 @@ sits there in red until `F North Sea convoys Yorkshire → Norway` joins it,
 and then both go black. Nothing was added to make that happen. The validator
 already knew.
 
+## Before the map, and how to stop
+
+A landing page, because Diplomacy has a reputation and about half of it is
+wrong. The rules are short enough to state completely and strange enough
+that stating them is a courtesy: there is no luck in this game at all, every
+unit is exactly as strong as every other, and nothing happens on the board
+that somebody did not agree to help with. It is also the honest place for
+the licence and for where the map came from -- a page that says nothing
+about that is a page quietly hoping nobody asks.
+
+The dice that play when you start are the only joke in here. There are no
+dice in Diplomacy; that is the sound of every other board game you have
+played, and the last one you hear before finding out that none of this is
+luck.
+
+Giving up is two different things and `src/game/concede.ts` keeps them
+apart.
+
+**Resigning is unilateral.** Nobody is entitled to your attention, so nobody
+votes on it. But your power does not leave the board: it goes into civil
+disorder, holds everything, waives its builds and is paid off as it loses
+centres, which is what the rules already say happens to an absent player.
+That matters to everybody else. A resigned Austria is still eleven centres
+somebody has to go and take, and letting them evaporate would hand the game
+to whoever happened to be next door.
+
+**A draw is not unilateral**, and that is the part that keeps it Diplomacy
+rather than a menu. Every surviving power votes and one refusal is enough,
+because being able to end the game by asking would be worth more than any
+alliance in it. A power refuses while it leads or is within two centres of
+leading, and it says so: *"England is 1 behind and thinks that is
+catchable."* Asked in Spring 1901 every one of the other six refuses, which
+is the right answer -- a game that could be drawn on the first turn would
+not be worth playing.
+
+**Conceding** -- handing the game to whoever is winning -- is harder to get
+than a draw, and it should be. It only carries when the solo was coming
+anyway: the leader is within four of eighteen and nobody left can close the
+gap. Otherwise refusing costs nothing but time, and time is the only thing
+the losing side has.
+
+Elimination is the third way out and needs no button. When your last centre
+goes you are told so and the rest plays out; you can watch it or close the
+tab, and either way the board is still worth seeing.
+
 ## Still to build
 
 - bots strong enough to solo against each other, not only to draw