This commit improves the README file so that it's more helpful
to documentation contributors. Especially, it:
- Adds the link to the prerequisites.
- Add information on troubleshooting (checking the links, headings, etc.)
- Removes the section on creating a knowledge base article, as we no longer
promote adding KBs in favor of creating a coherent documentation set.
Fixes https://github.com/scylladb/scylladb/issues/21257Closesscylladb/scylladb#21262
Commit 2a3012db7f ("docs/README.md: expand prerequisites list",
2022-08-31) referenced poetry release 1.12, which does not exist even
today (as of this writing, the latest release is 1.8.4). The intent was
probably 1.1.12.
Copy the minimum version from "sphinx-scylladb-theme": 1.8.1 (see
"docs/source/getting-started/installation.rst" and
"docs/source/getting-started/quickstart.rst" at commit f7c26b422572).
Signed-off-by: Laszlo Ersek <laszlo.ersek@scylladb.com>
