Prep repo for archiving (#89)

* Add README files

* Remove obsolete files

* Update README title

* Update README titles

* Remove obsolete folder

* Fix formatting

* fix bug

* Apply suggestions from review

README.md

@@ -1,77 +1,13 @@
 # Qiskit Textbook content
 
-> :warning: Unfortunately **we can't accept new pages to the textbook**. If you
-> have something you want to share with the community, we highly recommend you
-> self-publish. If you need help with self-publishing, or want feedback on your
-> work, contact Frank Harkins on the
-> [Qiskit Slack workspace](https://qisk.it/join-slack).
+This repository contains the source files for the Qiskit Textbook. Each page in
+the textbook is a Jupyter notebook in the [`notebooks`](./notebooks) folder.
 
-This is the repository for the Qiskit Textbook's content. This page is for
-people that want to report issues, or contribute to the Textbook, if you just
-want to read about quantum computing, go to [the textbook
-webpage](https://qiskit.org/learn/).
+> [!IMPORTANT] The Qiskit Textbook has been superseded by [IBM Quantum
+> Learning](https://learning.quantum-computing.ibm.com). These source files are
+> no longer maintained and may contain errors. We are not accepting any
+> contributions.
 
-If you've found a problem in the textbook, please [make a new
-issue](https://github.com/Qiskit/textbook/issues/new/choose).
-
-## Contributing
-
-OSX/Linux users can quickly set up by running
-
-```sh
-./install.sh
-source .venv/bin/activate
-```
-
-then
-```sh
-python -m jupyter notebook
-```
-
-Windows users should use [Git Bash](https://gitforwindows.org/) and Python version > 3.8 and < 3.11.
-
-```sh
-bash install.sh
-source .venv/Scripts/activate
-```
-
-then
-```sh
-python -m jupyter notebook
-```
-
-For a more detailed guide, please check out the
-[contributing document](./CONTRIBUTING.md).
-
-
-## Versioning
-
-We're constantly updating and improving the textbook, but some users find
-changes disruptive. For this reason, we release the Textbook content in
-_versions_, which are snapshots of the content that cannot change.
-
-The version number tells you what kind of changes have been made from the
-previous version. This repo follows a kind of [semantic
-versioning](https://semver.org/), adapted to make more sense for non-code
-repos.
-
-For a verision number `MAJOR.MINOR.PATCH`, we will increment the:
-
-- `MAJOR` version when changes remove or replace content,
-- `MINOR` version for changes that add content, or that do not significantly
-  alter the structure of existing pages. Examples include
-    - adding new pages,
-    - rewording paragraphs for clarity, and
-    - small changes to code to make it work with newer Qiskit versions.
-- `PATCH` version increments are for 'bugfixes' only. Examples include fixing
-    - typos,
-    - statements that are incorrect, and
-    - code that does not work correctly with the version of Qiskit advertised
-      on the page.
-
-For example, if you're teaching using `v1.0.3`, you know you can switch to any
-`v1.0.x` version without sections disappearing or code breaking with your
-existing setup.
 
 ## Bibtex citation