Update tags

[stropitek]

• Remove NMRium tags. It's the NMRium docs, everything is related to NMRium.
• Remove newsletter tag, I don't think it makes sense to be able to filter based on what was sent via the newsletter.
• Add "Release highlights" tag and add tags to articles appropriately. It can then be used in the "Release highlights" link in https://www.nmrium.com/tutorials/spectroscopists/overview/ to actually point only to the Release highlights articles.
• Replace the "info" tag with a "Teaching" tag, as both articles that have this tag are related to teaching.
• Remove the "documentation" tag. The article that has this tag does not need to be tagged.