[R-390] Reorganized 'References' page on our website

[Larry H]

Hi all,  The 'tutorials' section of the 'References' page on our website
has become very large and it could be easily split into 'repair'
tutorials and other types, so I split it in two that way.  To jump to a
desired section, click on its name in the contents.  Here's a direct link
to the References page: The R-390A References Page
<https://www.r-390a.net/faq-refs.htm>.

Regards, Larry