[docs] some examples does not print the output

There are a few articles that does not print the outputs. It's because their example code is just `res <- foo(...)` without printing the `res` (or avoiding assignment completely). Please grep the example code against this pattern. Few examples:
https://insightsengineering.github.io/chevron/main/reference/ael02.html#ref-examples
https://insightsengineering.github.io/chevron/main/reference/ael03.html#ref-examples

Start with the reference examples linked in the issue, especially ael02 and ael03, then grep the example code for assignments such as `res <- foo(...)`. Update affected examples so their output is printed or the assignment is avoided, and confirm the rendered articles show the example results.

Written by the indexing model from the issue text.