This PR fixes #57

Files for review:

• /exploring-the-universe/README.md

  • Preview: https://github.com/mikehoffms/Demos/blob/user/mikehoffms/explore-cosmos/exploring-the-universe/README.md
  • Updated the screenshot, and made it narrower.
  • Updated UI steps:
    • Added: Maximize the window (2x).
    • Changed from:
      click one of the headings in the right-hand Discoveries column, such as Laws of Planetary Motion (1609-1619).
      to:
      click one of the headings in the right-hand Discoveries column, such as Heliocentric Theory (1543).

• /exploring-the-universe/images/local-metrics-results.png

  • Updated the screenshot, and made it narrower.
  • Added the About this demo link.
  • Added the Precession of the Equinoxes (130 BC) heading.
  • Put the red box only around the heading within the expanded div, not around the entire div.

• exploring-the-universe/index.html

  • Changed the heading from:
    Precession of the Equinoxes (162-127 BC)
    to:
    Precession of the Equinoxes (130 BC)
  • Changed the heading from:
    Laws of Planetary Motion (1609-1619)
    to:
    Laws of Planetary Motion (1619)
  • Italicized Principia.

Source dir in PR branch:
https://github.com/mikehoffms/Demos/tree/user/mikehoffms/explore-cosmos/exploring-the-universe

AB# pending