Added videos category to the main categories

<label for="checkbox_{{ category|replace(' ', '_') }}">{{ _(category) }}</label>

{%- endmacro -%}

{% set main_categories = ["general", "images", "news"] %}

{% set main_categories = ["general", "images", "videos", "news"] %}

<div id="categories" {% if rtl %} class="rtl" {% endif %}>

{% for category in categories %}