[Migration] - Readtime

[hreikin]

I have done some minor work converting the readtime plugin from this repository to the namespace structure and would like to get it migrated across to the Plugin Organization if possible.

I have uploaded my work here if you would like to take a look. I have not included any tests as there were none in the original source. It isn't yet published to PyPi and the workflows are currently disabled in my repository.

Thanks

[hreikin]

After checking in on this I found the blog post about migrating plugins and have made a PR adding it to the documentation. With that being said, the readtime repo I linked in my initial post wasn't made following those steps, if you want me to redo everything first that's fine.

@justinmayer if the pelican team would like some help migrating some of these plugins I would love to volunteer some time as there are a few I would like to use which haven't been migrated yet.