feat: add optional hint/admonition icons (#383)

BREAKING CHANGE: The types of the `hint` short code have been renamed to `[note|tip|important|caution|warning]` the old types `[info|ok|warning|danger]` are still working, but should be considered as deprecated.

BREAKING CHANGE: The `hint` short code is using named arguments now. You have to change, e.g. `{{< hint warning >}}` to `{{< hint type=warning >}}`.

layouts/shortcodes/hint.html

@@ -1,3 +1,16 @@
-<blockquote class="gdoc-hint {{ .Get 0 }}">
-  {{ .Inner | $.Page.RenderString }}
+{{ $type := default "note" (.Get "type") }}
+{{ $icon := .Get "icon" }}
+{{ $title := default ($type | title) (.Get "title") }}
+
+
+<blockquote class="gdoc-hint {{ $type | lower }}">
+  <div class="gdoc-hint__title flex align-center">
+    {{ with $icon }}
+      <svg class="gdoc-icon {{ . }}"><use xlink:href="#{{ . }}"></use></svg>
+      <span>{{ $title }}</span>
+    {{ else }}
+      <i class="fa {{ $type | lower }}" title="{{ $title }}"></i>
+    {{ end }}
+  </div>
+  <div class="gdoc-hint__text">{{ .Inner | $.Page.RenderString }}</div>
 </blockquote>