Doesn't highlight Go string format placeholders

[jsvensson]

Version: Nord 0.1.1

The Nord theme is missing colors for constant.other.placeholder.go, which golang uses for Printf (etc) placeholders.

Example of the Solarized theme with the same line of Go code:

I don't really know my way around the theme, but I did a quick test using the escape character color:

<dict>
    <key>name</key>
    <string>[Go] String format placeholder</string>
    <key>scope</key>
    <string>source.go constant.other.placeholder.go</string>
    <key>settings</key>
    <dict>
        <key>foreground</key>
        <string>#EBCB8B</string>
    </dict>
</dict>

Good job on this color scheme, definitely one of my favorites!

[arcticicestudio]

Implemented in the referenced commit above.

[jsvensson]

It seems this change didn't make it into the switch from the tmTheme format to the JSON file.

edit: I'll add it to the JSON and make a PR.

[arcticicestudio]

I've used the builtin converter provided by VS Code to migrate to the new JSON format.
It seems like there have been some problems which are described in #12.