`retain_field` still in documentation and tutorials

[TobiasNx]

If I see right retain_field as function is deprecated, right? But there are still multiple references in the documentation and the tutorials:

e.g.: https://librecatproject.wordpress.com/2014/12/08/day-6-introduction-into-catmandu/ https://librecat.org/Catmandu/#fixes https://librecat.org/Catmandu/#convert-1 https://librecat.org/Catmandu/#cookbook https://librecat.org/Catmandu/#importexport

[vpeil]

Thanks for this hint. I've corrected the documentation and published it to the librecat.org website.

I am not going go fix the blog post.