bug#53574: csplit: help document: +/- is not required before OFFSET

[Jun-T]

'csplit --help' (and 'man csplit') says:
   A line OFFSET is a required '+' or '-' followed by a positive integer.

But I think the '+' or '-' is optional, not required.

'info csplit' just says:
   The optional OFFSET is an integer

I think this is correct since 'an integer' can be 3, +3 or -3.

--
Jun Takimoto