feat: add get reading time function

_includes/functions/get_reading_time.html

@@ -0,0 +1,41 @@
+{% if include.article %}
+  {% assign article = include.article %}
+{% endif %}
+
+{% if include.speed %}
+  {% assign speed = include.speed %}
+{% else %}
+  {% assign speed = 160 %}
+{% endif %}
+
+{% assign total_mins = article
+  | number_of_words
+  | divided_by: speed
+  | at_least: 1 %}
+
+{% assign hours = total_mins | divided_by: 60 %}
+{% assign mins = total_mins | modulo: 60 %}
+
+{% assign return = "About" %}
+
+{% if hours > 0 %}
+  {% assign unit = "hour" %}
+  {% if hours > 1 %}
+    {% assign unit = unit | append: "s" %}
+  {% endif %}
+  {% assign return = return
+    | append: " "
+    | append: hours
+    | append: " "
+    | append: unit %}
+{% endif %}
+
+{% assign unit = "min" %}
+{% if mins > 1 %}
+  {% assign unit = unit | append: "s" %}
+{% endif %}
+{% assign return = return
+  | append: " "
+  | append: mins
+  | append: " "
+  | append: unit %}