incorrect max-height in figure.html (alshedivat#1593)

figure.html was incorrectly setting height=max-height instead of
max-height=max-height

Author: NakuraMino

_includes/figure.html

@@ -22,7 +22,7 @@
       {% if include.min-width %}min-width="{{ include.min-width }}"{% endif %} 
       {% if include.min-height %}min-height="{{ include.min-height }}"{% endif %} 
       {% if include.max-width %}max-width="{{ include.max-width }}"{% endif %} 
-      {% if include.max-height %}height="{{ include.max-height }}"{% endif %} 
+      {% if include.max-height %}max-height="{{ include.max-height }}"{% endif %} 
       {% if include.alt %}alt="{{ include.alt }}"{% endif %} 
       {% if include.title %}title="{{ include.title }}"{% endif %} 
       {% if include.zoomable %}data-zoomable{% endif %}