Improvements to SPM web page

[Orv]

1. At the top of the Supported Product Matrix, it currently says
   "Current As of AREDN™ 3.21.4.0 (updated on 07/12/2021)"
   Recommended improvement:
   "Last updated on " If it's added via a nightly build, then it should be flagged as such (although I'm not sure how it's flagged with ** as listed at the bottom of the page)

2. Take the RED=STOP off the bottom since we don't typically post unsupported devices.

3. Do we still use the ORANGE=CAUTION"? If not it should be deleted.

4. Same with the "GREY=N/A".

5.And maybe we could increase interest by adding the products Joe is working on and highlighting them in Yellow (Researching).

[dman776]

changes made