Transfer Week 8 content from Moodle to QMD

[yangsophieee]

• Read through content and fixed some typos
• Changed format to fit our labelling station workflow: students will make their own labelled dataset and compare the trained model's accuracy to one trained on a larger dataset by Roxane
• Checked the code runs (did not check with the small labelled datasets that the students will make during class)
• Checked it renders

@dfalster I'm not exactly sure what the Moodle quiz will look like with the R chunk options, e.g. eval=FALSE. I am also not sure how embedded images get uploaded into Moodle.