solution_(s) drop their question parts when several versions are made.

[trinhdhk]

Hi,

Thank you for your super practical package.

One thing I found out when trying the package myself:
When different version (e.g. A, B) are made together with their respective solutions (solution_A, solution_B), the solutions' content no longer include the question's content. When there is one version, the solution behave just fine. I tried it out with your vignette source code and the issue still exist. I presume this is a bug by

all_info <- all_info %>%
    dplyr::select(-"solution")

in versions.R creating a duplicated tibble which is not properly handled later on. I forked the repo and did a quick fix.

all_info <- all_info %>%
    dplyr::select(-solution) %>%
    dplyr::group_by(starts, ends) %>%
    dplyr::summarise_all(any, na.rm = TRUE) %>%
    dplyr::ungroup()

Shall I make a pull request? Sorry I am new to the github workflow so just take an extra step of caution.