Added help text for most commands that take flags.

//generate, //regen, //deform, //[h]cyl, //[h]sphere, //chunk, //outset, //inset, //stack, //move, //smooth, //paste, //flip, /search //distr /butcher, //brush sphere/cyl/clipboard/smooth
Only //replace and /replacenear are still missing.

src/main/java/com/sk89q/worldedit/commands/UtilityCommands.java

@@ -346,6 +346,9 @@ public class UtilityCommands {
         usage = "[radius]",
         flags = "p",
         desc = "Kill all or nearby mobs",
+        help =
+            "Kills nearby mobs, or all mobs if you don't specify a radius.\n" +
+            "The -p flag makes /butcher also kill pets.",
         min = 0,
         max = 1
     )