[predefined-counter-styles] Add examples from css-counter-styles

Crissov has just created a new issue for 
https://github.com/w3c/predefined-counter-styles:

== Add examples from css-counter-styles ==
The specification for [CSS Counter Styles Level 
3](http://www.w3.org/TR/css-counter-styles-3/) contains several more 
or less useful examples for counters (or symbolic markers). Should 
they be repeated here?

I quote them below, slightly altered, for easy reference.

``` css
@counter-style triangle {
  system: cyclic;
  symbols: '‣';
  suffix: " ";
}

@counter-style box-corner {
  system: fixed;
  symbols: '◰' '◳' '◲' '◱';
  suffix: ': ';
}

@counter-style footnote {
  system: symbolic;
  symbols: '*' '⁑' '†' '‡';
  suffix: " ";
}

@counter-style upper-alpha-legal {
  system: symbolic;
  symbols: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z;
}

@counter-style go {
  system: alphabetic;
  symbols: '⚪️' '⚫️';
  suffix: " ";
}

@counter-style trinary {
  system: numeric;
  symbols: '0' '1' '2';
}

@counter-style dice {
  system: additive;
  additive-symbols: 6 '⚅', 5 '⚄', 4 '⚃', 3 '⚂', 2 '⚁', 1 '⚀';
  suffix: " ";
}

@counter-style decimal-paren {
  system: extends decimal;
  suffix: ") ";
}

@counter-style circled-lower-latin {
  system: alphabetic;
  speak-as: lower-latin;
  symbols: ⓐ ⓑ ⓒ ⓓ ⓔ ⓕ ⓖ ⓗ ⓘ ⓙ ⓚ ⓛ ⓜ ⓝ ⓞ ⓟ ⓠ ⓡ ⓢ ⓣ ⓤ ⓥ ⓦ ⓧ ⓨ ⓩ;
  suffix: " ";
}
```

The last one is actually already included.

See https://github.com/w3c/predefined-counter-styles/issues/10
Please do NOT reply to this email. If you'd like to contribute to the 
discussion, please do so at the above link. You will need to subscribe
 yourself to the issue (using the button provided by that page) to 
receive notifications of further comments.