Update to add N/A

src/get-dart/index.md

@@ -20,6 +20,7 @@ to develop and run Dart code.
 {% assign yes = '<span class="material-icons" style="color: #158477;">verified</span>' %}
 {% assign no = '<span class="material-icons" style="color: #D43324">dangerous</span>' %}
 {% assign beta = '<span class="material-icons" style="color: #13C2AD">gpp_maybe</span>' %}
+{% assign na = '<span class="material-icons" style="color: #DADCE0">do_not_disturb_on</span>' %}
 {% assign macversions = '' %}
 {% for version in site.data.macos limit:3 %}
 {%- if version.eol == false -%}
@@ -35,10 +36,13 @@ to develop and run Dart code.
 |----------|---------|---------|---------|-----------|-----------|------------------------------------------|
 | Windows  | {{yes}} | {{yes}} | {{no}}  | {{beta}} | {{no}}    | [10] (32-bit, 64-bit), [11][]                                   |
 | Linux    | {{yes}} | {{yes}} | {{yes}} | {{yes}}   | {{beta}} | [Debian stable][], [Ubuntu LTS][]        |
-| macOS    | {{no}}  | {{yes}} | {{no}}  | {{yes}}   | {{no}}    | {{macversions}} |
+| macOS    | {{no}}  | {{yes}} | {{na}}  | {{yes}}   | {{na}}    | {{macversions}} |
 {:.table .table-striped}
 
-{{beta}} Supported in Dev, Beta channels only.
+{{yes}} Supported in all channels.  
+{{no}} Unsupported in all channels.  
+{{beta}} Supported in Dev, Beta channels only.  
+{{na}} No version exists.
 
 ## Choose an install option