s3 tutorials and documentation

[jankounchained]

S3 documentation currently says that PCA is an option. https://github.com/x-tabdeveloping/turftopic/blob/main/docs/s3.md

We should update the documentation to show:

• a quickstart tutorial with only ICA
• one mention and example of "you can use almost any decomposition method"
• how to display and interpret axis top terms (high and low)
• how to visualize the topic model – hard. Could be a word map, but markers cannot be colored by dominant topic (not how s3 works). I would love a worked example with document map, for example, a written out yelp reviews example similar to what we did with @Rnault (see screenshot to remind)