[documentation] Better document webshot / webshot2 usage

[pawelru]

---

By filing an issue to this repo, I promise that

• I have fully read the issue guide at https://yihui.org/issue/.
• I have provided the necessary information about my issue.
  • If I'm asking a question, I have already asked it on Stack Overflow or RStudio Community, waited for at least 24 hours, and included a link to my question there.
  • If I'm filing a bug report, I have included a minimal, self-contained, and reproducible example, and have also included xfun::session_info('knitr'). I have upgraded all my packages to their latest versions (e.g., R, RStudio, and R packages), and also tried the development version: remotes::install_github('yihui/knitr').
  • If I have posted the same issue elsewhere, I have also mentioned it in this issue.
• I have learned the Github Markdown syntax, and formatted my issue correctly.

I understand that my issue may be closed if I don't fulfill my promises.

---

Would you mind document better the usage / availability of webshot / webshot2? Actually I get to know that I can use webshot2 only after reading GH discussions on already closed issue, namely #2276 (comment). (as a side note - only using webshot2 I could solve the issue). When I googled this topic for the very first time I end up on an article in your bookdown book which also does not mention webshot2. For people with the same issue as mine, it would be great to have it listed somewhere in the Chunks Option article or anywhere in the docs.

[cderv]

Thanks for the feedback !

This is indeed a great suggestion - we'll see where is the best place to document this.