Typo - Chp 2, Sec 2.1.2, observation should be observations

[staceyhancock]

• Chapter number: 2

• Section number: 2.1.2

• Other location identifier, if any (e.g., figure number, table number, footnote number, etc.): 02-data-design.Rmd line 60

• Original text: A numerical summary can be calculated on either the sample of observation or the entire population.

• Suggestion for corrected text: A numerical summary can be calculated on either the sample of observations or the entire population.

• Justification for suggestion: Fix typo