Fixed commands prefix in detailed help commands

[kreicer]

Example:

!help roll

Output:

![roll|r] dice_1 [dice_2... dice_n]

Roll different type of dice in one roll:
- single die, single roll: ?roll d20
- single die, multiple rolls: ?roll 10d4
- multiple dice, single roll: ?roll d4 d8 d20
- multiple dice, multiple rolls: ?roll 4d8 4d4 2d20
- co-co-combo: ?roll d20 5d10 d100 d12

Issue with ?roll cos bot can use different prefix.

[kreicer]

Fixed. Now detailed help give back current prefix, not predefined.