Merge branch '695-test-installation-docs' into 'master'

Resolve "Test installation docs"

Closes #695

See merge request !1042

docs/admin/01_core_concepts.rst

+.. _core-concept:
+
 Concepts of the AlekSIS core
 ============================
 

docs/admin/10_install.rst

@@ -55,7 +55,8 @@ Install some packages from the Debian package system.
                chromium \
                redis-server \
                postgresql \
-               locales-all
+               locales-all \
+               celery
 
 Create PostgreSQL user and database
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -78,7 +79,6 @@ Create the directories for storage
             /usr/share/aleksis/{static,node_modules} \
             /var/lib/aleksis/media \
             /var/backups/aleksis
-   chown -R www-data:www-data /var/lib/aleksis
 
 Create AlekSIS configuration file
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -111,6 +111,18 @@ favourite text editor and adding the following configuration.
    password = "admin"
    email = "root@localhost"
 
+Make sure you specify the correct `allowed_hosts`. It is used for things like the OpenID Connect issuer and the standard mail domain.
+
+Generate OpenID Connect certificate
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+OpenID Connect needs a certificate, which you need to generate and assign required permissions.
+
+.. code-block:: shell
+
+   openssl genrsa -out /etc/aleksis/oidc.pem
+   chown www-data:www-data /etc/aleksis/oidc.pem
+
 Install AlekSIS itself
 ~~~~~~~~~~~~~~~~~~~~~~
 
@@ -119,14 +131,30 @@ They will pull the AlekSIS standard distribution from `PyPI`_ and install it to
 system-wide `dist-packages` of Python. Afterwards, it will download frontend dependencies
 from `yarnpkg`, collect static files, and migrate the database to the final schema.
 
+`aleksis` is a meta-package which will install the :ref:`core-concept`  and all official apps. If you want to install only the AlekSIS Core and your own set of apps, you can install `aleksis-core` instead of `aleksis`.
+
+You only need to install these additional dependencies if installing the meta-package:
+
 .. code-block:: shell
+   apt install libmariadb-dev libldap2-dev libsasl2-dev
+
+After that, you can install the aleksis meta-package, or only `aleksis-core`:
 
+.. code-block:: shell
    pip3 install aleksis
    aleksis-admin yarn install
    aleksis-admin collectstatic
    aleksis-admin migrate
    aleksis-admin createinitialrevisions
 
+Make dynamic content writable for webserver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To make AlekSIS® able to write dynamic content, you need to assign permissions to the webserver user.
+
+.. code-block:: shell
+   chown -R www-data:www-data /var/lib/aleksis
+
 .. _core-configure-uwsgi:
 
 Configure uWSGI