[GNC-dev] Sample Report with Examples

[flywire]

The Sample Report with Examples is one of those gems in GnuCash that take a
bit of finding but it's well worthwhile working through it when you do. I'd
like to see the first paragraph changed to emphasise its purpose and add
the wiki reference in the second paragraph. Something like:

> This report is a sample demonstration using source code and options to
introduce you to writing reports. You can make changes and see the effects.
The guile (scheme) source code in the scm/report directory has comments on
extending existing reports or writing your own.
>
> More help on writing reports is available at
https://wiki.gnucash.org/wiki/Custom_Reports (including report location) or
consult the mailing list gnucash-devel at gnucash.org where you could
contribute your brand new, totally cool report. For details on subscribing
to that list, see <https://www.gnucash.org/>. You can learn more about
writing scheme at <https://www.scheme.com/tspl2d/>.

The code would be easier to follow if different strings other than Hello,
World! were used, making it clearer what they relate to. While this report
might have developed from a Hello World example, a minimal program to
generate output, it's much more than that now. Can it be renamed? Maybe
just hello.scm or move it to welcome-to-gnucash.scm with a related document
title.

If there are no concerns I'll put up a PR.