doc: added binder explanation

README.md

@@ -1,5 +1,6 @@
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/zerothi/ts-tbt-sisl-tutorial?label=tutorial)
 [![Join discussion on Discord](https://img.shields.io/discord/742636379871379577.svg?label=&logo=discord&logoColor=ffffff&color=green&labelColor=red)](https://discord.gg/bvJ9Zuk)
+[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/zerothi/ts-tbt-sisl-tutorial/2021?filepath=tutorial.ipynb)
 
 Welcome to sisl + TBtrans + TranSiesta tutorial
 ===============================================
@@ -14,8 +15,25 @@ The sources used for these tutorials can be found elsewhere:
 - [Siesta][tbtrans] (>= 4.1.5)
 
 
+
+Binder
+------
+
+This tutorial may be runned using [Binder](https://mybinder.readthedocs.io/en/latest/).
+Note that we highly recommend using a local Conda installation since that is much
+more versatile and since this tutorial requires lots of text-editing which is hard
+to do in a Jupyter notebook.
+
+However, if you want to play around you may do so, for a good experience you are
+recommended to execute tbtrans like this:
+
+    !OMP_NUM_THREADS=1 tbtrans RUN.fdf
+
+since the installed `tbtrans` is threaded and binder is sharing resources.
+
+
 <!---
 Links to external and internal sites.
 -->
 [sisl@git]: https://github.com/zerothi/sisl
-[tbtrans]: https://launchpad.net/siesta
+[tbtrans]: https://gitlab.com/siesta-project/siesta