TODO:
/**
* Renders a block of text based on the provided condition.
*
*
* @example
*
*
* # 1: Show only on product page.
*
* {{condition key="{{$post.post_name}}" operation="equal" value="product"}}
* <p>This is the product page!</>
* {{/condition}}
*
*
* # 2: Show on every page but product.
*
* {{condition key="{{$post.post_name}}" operation="not" value="product"}}
* <p>This is not the product page!</>
* {{/condition}}
*
*
* # 3: Show if matching a regex.
*
* {{condition key="{{$post.post_permalink}}" operation="match" value="/free/"}}
* <p>This promotion will expire soon!</p>
* {{/condition}}
*
*
* # 4: Show on certain date.
*
* {{condition key="{{date format='Y-m-d'}}" operation="match" value="2017-02-28"}}
* <p>Today is the date!</p>
* {{/condition}}
*
*
* # 5: Show after certain date.
*
* {{condition key="{{date format='Y-m-d'}}" operation=">" value="2017-02-28"}}
* <p>Sorry, you missed it :-(</p>
* {{/condition}}
*
*
*/