[csswg-drafts] Pull Request: [css-grid] Update grid shorthand example to the new syntax

mrego has just submitted a new pull request for 
https://github.com/w3c/csswg-drafts:

== [css-grid] Update grid shorthand example to the new syntax ==
The grid shorthand syntax was changed in commit 5fde09cd,
but the example was not updated by that time.

See https://github.com/w3c/csswg-drafts/pull/465