Without further context, I would say this formal response is appropriate in a business setting.
If the person is expecting only one issue to be updated then the singular form could be used. Normally, the issue(s) would either be understood or mentioned previously in the correspondence.
I look forward to receiving your update
For a slightly less formal approach
I look forward to receiving updates in the year/future ahead
........................................................ in the coming months
The following is the most common formal request for any news
I-or-We look forward to hearing from you
The OP's second suggestion is nearly perfect, I would only add a please to make the request more polite.
Please, keep me updated.
The OP could also add the following condition
............................... as and when the documents are ready, thank you.
There are many types of informal requests for news that are appropriate between friends, these are just three off the top of my head.
- Let me know what's happening/going on
- Don't forget to keep me updated
- As soon as you get any info drop me a line