README: Add the settings for server owners, minor edits.

Drop 0.4.12 compatibility

README.txt

@@ -1,8 +1,8 @@
  Minetest mod: boost_cart
 ==========================
 Based on (and fully compatible with) the mod "carts" by PilzAdam
-Also compatible with the carts mod in the subgame "minetest_game".
-Target: Run smoothly as possible even on laggy server
+and the one contained in the subgame "minetest_game".
+Target: Run smoothly as possible, even on laggy servers.
 
 
  Features
@@ -12,8 +12,25 @@ Target: Run smoothly as possible even on laggy server
 - Boost and brake rails
 - By mesecons controlled Start-Stop rails
 - Detector rails that send a mesecons signal when the cart drives over them
-- Rail junction switching with the 'right-left' walking keys
+- Rail junction switching with the 'right/left' walking keys
 - Handbrake with the 'back' key
+- Support for non-minetest_game subgames
+
+
+ Settings
+----------
+This mod can be adjusted to fit the conditions of a player or server.
+Use the Advanced Settings dialog in the main menu or tune your
+minetest.conf file manually:
+
+boost_cart.speed_max = 10
+   ^ Possible values: 1 ... 100
+   ^ Maximal speed of the cart in m/s
+
+boost_cart.punch_speed_max = 7
+   ^ Possible values: -1 ... 100
+   ^ Maximal speed to which the driving player can accelerate the cart
+     by punching from inside the cart. -1 will disable this feature.
 
 
  License for everything