*QIIME 2 for experienced microbiome researchers*: general updates needed

[gregcaporaso]

I made some small updates while translating the document to MyST markdown, but this could use more updating. For example:

• link to some representative visualizations in here - e.g., from the QIIME 2 View gallery
• add some discussion of viewing Artifacts as metadata
• add some discussion of q2-vizard and q2-stats