add figure-img-size shortcode

for controlling image size with <figure>

assets/css/common/main.css

@@ -224,6 +224,10 @@ figure > img {
     text-align: center;
 }
 
+.image-size-control {
+    margin-left: auto;
+    margin-right: auto;
+}
 .image-size-control > img {
     width: inherit;
     height: inherit;

layouts/shortcodes/figure-img-size.html

@@ -0,0 +1,12 @@
+{{- $width := .Get 1 }}
+{{- $height := .Get 2 }}
+<figure class="center align-center">
+  <div class="image-size-control" style="
+{{- with $width }}max-width: {{ . }};{{ end -}}
+{{- with $height }}max-height: {{ . }};{{ end -}}
+">
+    {{ .Page.RenderString .Inner }}
+  </div>
+
+  <figcaption><p>{{ .Get 0 | markdownify }}</p></figcaption>
+</figure>