Add documentaton for dataset README.md files
Hi ! We are using the [datasets-tagging app](https://github.com/huggingface/datasets-tagging) to select the tags to add.

We are also adding the full list of tags in #2107 
This covers multilinguality, language_creators, licenses, size_categories and task_categories.

In general if you want to add a tag that doesn't exist (for example for a custom license) you must make it start with `other-` and then a custom tag name.

edit (@theo-m) if you ever find yourself resorting to adding an `other-*` tag, please do ping us somewhere so we can think about adding it to the "official" list :)
Hi,
the dataset README files have special headers.
Somehow a documenation of the allowed values and tags is missing.
Could you add that?

Just to give some concrete questions that should be answered imo:
- which values can be passted to multilinguality?
- what should be passed to language_creators?
- which values should licenses have? What do I say when it is a custom license? Should I add a link?
- how should I choose size_categories ? What are valid ranges?
- what are valid task_categories?

Thanks
Philip
Add documentaton for dataset README.md files 
 Hi,
the dataset README files have special headers.
Somehow a documenation of the allowed values and tags is missing.
Could you add that?

Just to give some concrete questions that should be answered imo:
- which values can be passted to multilinguality?
- what should be passed to language_creators?
- which values should licenses have? What do I say when it is a custom license? Should I add a link?
- how should I choose size_categories ? What are valid ranges?
- what are valid task_categories?

Thanks
Philip 
 Hi ! We are using the [datasets-tagging app](https://github.com/huggingface/datasets-tagging) to select the tags to add.

We are also adding the full list of tags in #2107 
This covers multilinguality, language_creators, licenses, size_categories and task_categories.

In general if you want to add a tag that doesn't exist (for example for a custom license) you must make it start with `other-` and then a custom tag name.

edit (@theo-m) if you ever find yourself resorting to adding an `other-*` tag, please do ping us somewhere so we can think about adding it to the "official" list :)