The neat thing about not indenting it is that you can make use of your editor's text-width auto-wrapping. For example, if you have it set to 80 columns, indenting it would make the text-width of the help text 76 in your case.

Also, putting the help text in code like this instead of a comment allows one to expand $0 so that the command name in the help text always matches the filename and path used in the invocation.