What it says on the tin. This just updates the `bump-version.nu` script
to also edit the version in
the new nu_plugin_nu_example plugin, the same way it does for python
* add `bump-version.nu` to bump a version automatically
* mention `bump-version` in the release guide insted of `sd`
* remove the Note about `sd`ing the `Cargo.lock` file
* break very long lines
* find and replace in the `.nu` config files only
* fix the `str expand` command call for windows
it appears to not work properly with the `\` introduced by `path join`.
