Update script_commands.txt

Added documentation for switch statement.

doc/script_commands.txt

@@ -1964,6 +1964,64 @@ with this command when a script is parsed.
 
 ---------------------------------------
 
+*switch (expression);
+
+The switch statement is similar to a series of if statements on the same expression.
+In many occasions, you may want to compare the same variable (or expression)
+with many different values, and execute a different piece of code depending
+on which value it equals to. This is exactly what the switch statement is for.
+
+It is important to understand how the switch statement is executed in order
+to avoid mistakes. The switch statement executes line by line (actually, statement by statement).
+In the beginning, no code is executed. Only when a case statement is found
+with a value that matches the value of the switch expression the case statement(s)
+will to executed. The parser continues to execute the statements until the end
+of the switch block, or the first time it sees a break statement. If you don't
+write a break statement at the end of a case's statement list, the parser will
+go on executing the statements of the following case (fall-through).
+
+Example 1:
+	
+	switch(select("Yes:No")) {
+		case 1:
+			mes "You said yes!";
+			break;
+		case 2:
+			mes "Aww, why?";
+			break;
+	}
+	close;
+
+The example above would work like a menu and would go to the first case if
+the user selects option, otherwise, would go to the second one.
+
+Example 2:
+	
+	switch(getgroupid()) {
+		case 1:
+			mes "Wow, you're super!";
+			break;
+		case 2:
+			mes "A helping hand!";
+			break;
+		case 3:
+			mes "10001010010011";
+			break;
+		case 4:
+			mes "Yes, milord?";
+			break;
+		default:
+			mes "Hello there!";
+			break;		
+	}
+
+The example above would print a message depending on the player's groupid.
+If there is no statement declared for the corresponding groupid, the script
+would use the 'default' statement that applies to rest of possible values,
+similar to 'else' in the if-else statement.
+
+---------------------------------------
+
 *while (<condition>) <statement>;
 
 This is probably the simplest and most frequently used loop structure. The 'while'