Adding new page for CSS Grid Animation support

Attempt No 2. 
As discussed in Fyrd#6298.
Supported in Firefox since FF66. https://hacks.mozilla.org/2019/03/firefox-66-the-sound-of-silence/
Supported in Safari 16 and STP. https://developer.apple.com/documentation/safari-release-notes/safari-16-release-notes
Not supported in Chromium browsers (I tested using CodePen demo at https://css-irl.info/animating-css-grid/)