<!--
if this PR closes one or more issues, you can automatically link the PR
with
them by using one of the [*linking
keywords*](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword),
e.g.
- this PR should close #xxxx
- fixes #xxxx
you can also mention related issues, PRs or discussions!
-->
# Description
<!--
Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.
Description of your pull request goes here. **Provide examples and/or
screenshots** if your changes affect the user experience.
-->
I was interested in how nu-shell handles glibc, especially older
versions of it. I figured out from the docs that ubuntu 20.04 is
utilized. However, in reality, github has deprecated ubuntu 20.04, and
the code for ci.yaml in github workflow clearly states that it is 22.04.
This is just a minor doc update to clarify forgotten information
# Description
Removes the old `nu-cmd-dataframe` crate in favor of the polars plugin.
As such, this PR also removes the `dataframe` feature, related CI, and
full releases of nushell.
This is still work in progress. But let's start somewhere.
Goal for this being in the repo is to make sure we update it more
frequently than the
https://github.com/nushell/nushell.github.io/tree/main/contributor-book
- Add folder for in-repo developer documentation
- Move PLATFORM_SUPPORT into devdocs
- Move our rust style to devdocs
- Use nushell code formatting in CONTRIBUTING
- Add FAQ file for developers with example questions
- Describe error handling best practices
