Add docs about installation

docs/admin/01_install.rst

+Install AlekSIS
+===============
+
+From source
+-----------
+
+In this section we will install AlekSIS with `uWSGI` and `nGINX` on debian
+bullseye.
+
+0. Prerequisites::
+
+ * Debian 11
+ * 
+
+1. Prepare system
+
+  * Install system dependencies::
+
+    $ apt install uwsgi uwsgi-plugin-python3 nginx-full python3.9 python3.9-dev
+libldap2-dev libsasl2-dev yarnpkg python3-virtualenv
+  * Create and activate virtual environment::
+
+    $ mkdir -p /srv/www/aleksis
+    $ mkdir -p /srv/www/aleksis/data/{static,media}
+    $ cd /srv/www/aleksis
+    $ virtualenv -p python3 --system-site-packages venv
+    $ source /srv/www/aleksis/venv/bin/activate
+    $ pip install poetry
+
+  * Install and configure PostgreSQL::
+
+    $ apt install postgresql-13
+    $ sudo -u postgres createuser -l aleksis -
+    $ sudo -u postgres createdb -O aleksis aleksis
+
+  * Configure uWSGI::
+
+    $ editor /etc/uwsgi/apps-available/aleksis.ini
+
+    [uwsgi]
+    vhost = true
+    plugins = python3
+    master = true
+    enable-threads = true
+    processes = 20
+    wsgi-file = /usr/src/AlekSIS/aleksis/core/wsgi.py
+    virtualenv = /srv/www/aleksis/venv
+    chdir = /usr/src/AlekSIS
+    lazy = true
+    lazy-apps = true
+
+    $ ln -s /etc/uwsgi/apps-available/aleksis.ini /etc/uwsgi/apps-enabled/aleksis.ini
+    $ service uwsgi restart
+
+  * Configure nGINX::
+
+    $ editor /etc/nginx/sites-available/my.aleksis-instance.com
+
+      server {
+        listen 80;
+        listen [::]:80;
+
+        server_name my.aleksis-instance.com my.aleksis-instance.com;
+
+        return 301 https://$server_name$request_uri;
+      }
+
+      server {
+              listen 443 ssl http2;
+              listen [::]:443 ssl http2;
+
+              ssl_certificate /var/lib/dehydrated/certs/my.aleksis-instance.com/fullchain.pem;
+              ssl_certificate_key /var/lib/dehydrated/certs/my.aleksis-instance.com/privkey.pem;
+              ssl_trusted_certificate /var/lib/dehydrated/certs/my.aleksis-instance.com/chain.pem;
+
+              server_name my.aleksis-instance.com my.aleksis-instance.com;
+
+              access_log /var/log/nginx/access.log;
+
+              location /static {
+                      alias /srv/www/aleksis/data/static;
+              }
+
+              location / {
+                      uwsgi_pass aleksis;
+                      include uwsgi_params;
+
+                      proxy_redirect off;
+                      proxy_pass_header Authorization;
+              }
+      }
+
+    $ ln -s /etc/nginx/sites-available/my.aleksis-instance.com /etc/nginx/sites-enabled/my.aleksis-instance.com
+    $ service nginx restart
+
+  * Configure AlekSIS::
+
+    $ mkdir /etc/aleksis
+    $ editor /etc/aleksis/aleksis.toml
+
+      static = { root = "/srv/www/aleksis/data/static", url = "/static/" }
+      media = { root = "/srv/www/aleksis/data/media", url = "/media/" }
+      secret_key = "SomeRandomValue"
+
+      [http]
+      allowed_hosts = ["my.aleksis-instance.com"]
+
+      [database]
+      host = "localhost"
+      name = "aleksis"
+      username = "aleksis"
+      password = "SomeSecretPassword!1"
+
+
+2. Clone git-Repository and checkout version::
+
+  $ cd /usr/src
+  $ git clone https://edugit.org/AlekSIS/official/AlekSIS-Core
+  $ cd AlekSIS-Core
+  $ git checkout 2.0b
+
+5. Install Dependencies and setup initially::
+
+  $ poetry install
+  $ aleksis-admin yarn install
+  $ aleksis-admin collectstatic
+
+Docker
+------
+
+.. _Dynaconf: https://dynaconf.readthedocs.io/en/latest/