Incorrect Javadoc in SimpleStepBuilder

[fmbenhassine]

The Javadoc on SimpleStepBuilder is incorrect here:

Step builder for simple item processing (chunk oriented) steps. Items are read and cached in chunks,
and then processed (transformed) and written (optionally either the processor or the writer can be omitted)
all in the same transaction.

The item writer is mandatory in a chunk-oriented step, only the item processor is optional. The goal of this issue is to change the Javadoc as follows:

--optionally either the processor or the writer can be omitted
++optionally the processor can be omitted

[seonWKim]

Hi @fmbenhassine, thank you for the "first-timers-only" issue. May be I can start my contribution to spring batch from here 😄 . I've created a PR.

[fmbenhassine]

@seonwoo960000 Great! Thank you for your help and for opening your first PR 🎉

[seonWKim]

@fmbenhassine It's a pleasure. Hope to contribute more to greate spring batch project.