left.
Because an asterisk at the end of a word signifies that there is something special about that term or the expression it's a part of (usually a reference or further information) and the asterisk before a word means that what follows it is said reference or information about a term or expression.
So in this case since you add an information about a previously written term or sentence (namely correcting a fault) you should put the asterisk at the start of it to represent that.
Theoritically you should also put an asterisk at the end the word you're correcting but since this is (usually) used because you can't edit the message you're correcting we'll settle for simply putting an asterik at the beginning and letting the reader figure out what you're correcting.
Caption this Meme
