HACKING file in gnucash-docs

[John Ralls]

> On Dec 3, 2016, at 10:39 PM, David T. via gnucash-devel <gnucash-devel at gnucash.org> wrote:
> 
> Hello,
> 
> I took a look today at the HACKING file included with the GnuCash docs, and I believe that it is out of date, at least because it references subversion. There may be other outdated bits included, but I am not informed enough to know what this document should say instead. I wanted to raise the issue here so that this file can get updated to current practice and procedure.

We should simply replace its contents with a single link to the wiki Development page.

Regards,
John Ralls