details.tmpl: make latest-version link for std to go std
Fixes b/144117641.
<div class="DetailsHeader-version">{{$header.Version}}</div>
<div class="DetailsHeader-badge"
data-version="{{$header.Version}}"
- {{ if eq $namespace "mod" -}}
+ {{if eq $namespace "mod" }}
data-mpath="{{$header.Path}}"
+ {{if eq $header.Path "std" }}
+ data-href="{{$header.Path}}">
+ {{- else -}}
data-href="mod/{{$header.Path}}">
+ {{- end -}}
{{- else -}}
data-mpath="{{$header.Module.Path}}"
data-ppath="{{$header.Path}}"
