So now we install a specific version of Node.js and use the packages
required for Debian Bookworm.
For consistency, we're also making them similar to the Ubuntu
instructions and installing rbenv instead of RVM. Since we now suggest
rbenv in both cases as well as in the macOS instructions, we're also
listing rbenv as the first option in the generic local installation
instructions.
We were following it about half of the time and we even added it to our
former `.mdlrc` file. However, for some reason, MDL doesn't detect this
rule when specified in the `.mdlrc` file, so we didn't notice we weren't
following it in many cases.
Now that we're using a style file to configure MDL, we can enable this
rule again and apply it, since now MDL correctly includes it in its
report.
Note that, in order to have some consistency, we're always writing
"Consul Democracy", instead of using capital letters sometimes (but not
always), like we did until now.
This is the Ruby version CONSUL uses now. Thanks to that, we no longer
need to install an old version of libssl-dev for Ubuntu 18.04.
We could probably simplify the documentation using:
```bash
rbenv install `cat .ruby_version`
```
However, this would require downloading consul before installing Ruby,
which could be harder to document.
