prepare blog post for blog.datalad.org about registry.datalad.org instance

[yarikoptic]

somewhat similar to distribits talk, so can link youtube video with that talk, but may be demonstrate more

• cover the https://github.com/datalad/datalad-usage-dashboard/ setup which automatically discovers datalad datasets on various hosting platforms (not yet on https://codeberg.org/matrss/forgejo-aneksajo , issue datalad/datalad-usage-dashboard#47)
• show that they then get indexed on registry https://registry.datalad.org/overview/
• show that we provide stats on total or results of search
• demonstrate some search capabilities

@asmacdo has had experience already in composing similar blog post on con-duct, so would be great if you work together to prepare a blog post on registry.