New Featue : Support rest-docinfo metadata for nikola

[mandarvaze]

Recently nikola started supported variety of metadata formats.

Currently, the posts with the following style of meta-data format say "Can't Parse"

:title: My Title
:slug: my-title
:date: 2012-09-15 19:52:05 UTC

By supporting https://getnikola.com/handbook.html#rest-docinfo , you may be able to support pelican blog platform with blog-admin