Make links in `Capybara` module API doc
Make links in `Capybara` module API doc

This changes plain-text references to links in the `Capybara` module as possible.
Also, this fixes incorrect references and typos.

This change is extracted from #2190.

jnicklas/capybara,jnicklas/capybara,teamcapybara/capybara,teamcapybara/capybara,teamcapybara/capybara,jnicklas/capybara