[R-390] Two recent changes to our website

[Larry H]

Hi all,  I've made two recent changes to our website, r-390a.net.

1. Changed the link to the 'contract numbers' file by Tom Marcotte to a new
updated file linked to on our *'**Manufacturers' *page.  Here's a direct
link to the new file: R390a R390 R391 Production Notes.pdf (r-390a.net)
<https://www.r-390a.net/R390a%20R390%20R391%20Production%20Notes.pdf>

2. Added a link to Jim Miller's A JOURNEY THROUGH THE COSMOS (PTO)
<http://www.r-390.com/cosmos.htm> on our 'Reference' page in the
'Tutorials' section.

Enjoy.

Regards, Larry