DOC: Add tutorial: how to setup devel environment

I find out that this cannot be just a generic tutorial in framework
as in case of leapp-repository people needs to register the upgrade
repositories explicitely. So let's do it in this way.

docs/source/tutorials/index.rst

@@ -3,12 +3,21 @@ Tutorials
 
 Tutorials here are focused on In-Place Upgrades with leapp repositories
 covered by the `leapp-repository <https://github.com/oamg/leapp-repository>`_ project.
+Therefore the main focus of these tutorials is to provide information how to
+write leapp actors for **In-Place Upgrades (IPU)** with the leapp framework.
+
+.. note::
+    These tutorials are under reconstruction and we will be glad for a feedback.
+    Feel free to contact us via `GH discussion <https://github.com/oamg/leapp-repository/discussions>`_
+    in our upstream project.
+
 
 .. toctree::
     :maxdepth: 4
     :caption: Contents:
     :glob:
 
+    setup-devel-env
     howto-first-actor-upgrade
     custom-content
     templates/index

docs/source/tutorials/setup-devel-env.md

@@ -0,0 +1,50 @@
+# How to setup the development environment
+
+To ensure you can follow the other guidelines, here we are adding tips how
+to prepare your development environment.
+
+## Clone official leapp repositories for IPU
+
+If you are creating your custom content for IPU or want to contribute to the
+upstream leapp-repository project, most likely you will want to have the
+repository cloned to be able to
+* get insipration from existing content
+* search what you could use from the prepared content (shared libraries,
+existing models, ...)
+* etc.
+
+Simply clone the [official upstream repository](https://github.com/oamg/leapp-repository) using Git:
+```shell
+git clone [email protected]:oamg/leapp-repository.git
+```
+
+In case you want to contribute to the upstream project, [fork the repository](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo).
+
+## Install snactor
+Simply follow instructions in the leapp tutorials [here](https://leapp.readthedocs.io/en/latest/devenv-install.html)
+
+## Register IPU repositories in snactor
+
+By default, repositories on your system are not registered for snactor unless
+you created them on your system with snactor directly. So typically `snactor`
+commands working with existing repositories does not work correctly. To register
+all wanted repositories, go to the cloned leapp-repository repository and make
+snactor to search all repos:
+```shell
+snactor repo find --path repos/
+```
+
+This will register all leapp repositories in the project. You can list all
+registered repositories with snactor using: `snactor repo list`.
+
+The configuration file with registered repositories is by default here: `~/.config/leapp/repos.json`
+
+```{warning}
+If you are on system with installed `leapp-upgrade-*` RPMs and you register
+the upgrade repositories from installed packages using `snactor`, it's possible it will
+not be the best idea to register also repositories from the cloned Git repository.
+In such a case we suggest to use different config files when trying
+to work with snactor in one or the other set of repositories. See the `--config`
+option. You can also always clear the file and re-register repositories you
+want again.
+```