Move setup process via script into container (#2174)

Decoupling setup process from `setup.sh` script by introducing a setup script _inside_ the container that coordinates the setup process.

**This is not a breaking change**. This way, we do not have to keep track of versions of `setup.sh`.

This change brings the additional benefit for Kubernetes users to be able to make use of `setup` now, without the need for `setup.sh`.

---

* move setup process into container; setup.sh versioning not needed anymore

* add tilde functionality to docs

Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>
Co-authored-by: Casper <casperklein@users.noreply.github.com>

docs/content/config/setup.sh.md

@@ -1,7 +1,7 @@
 ---
 title: Your best friend setup.sh
 hide:
-  - toc # Hide Table of Contents for this page
+  - toc
 ---
 
 [`setup.sh`][github-file-setupsh] is an administration script that helps with the most common tasks, including initial configuration. It is intended to be used from the host machine, _not_ from within your running container.
@@ -13,13 +13,9 @@ wget https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/maste
 chmod a+x ./setup.sh
 ```
 
-!!! info
-
-    Make sure to get the `setup.sh` that comes with the release you're using. Look up the release and the git commit on which this release is based upon by selecting the appropriate tag on GitHub. This can done with the "Switch branches/tags" button on GitHub, choosing the right tag. This is done in order to rule out possible inconsistencies between versions.
-
 ## Usage
 
-Run `./setup.sh help` and you'll get some usage information:
+Run `./setup.sh help` and you'll get ~~all you have ever wanted~~ some usage information:
 
 ```TXT
 SETUP(1)
@@ -55,28 +51,6 @@ VERSION
     following URL, where TAG looks like 'vX.X.X':
     https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/TAG/setup.sh
 
-OPTIONS
-    Config path, container or image adjustments
-        -i IMAGE_NAME
-            Provides the name of the docker-mailserver image. The default value is
-            docker.io/mailserver/docker-mailserver:latest
-
-        -c CONTAINER_NAME
-            Provides the name of the running container.
-
-        -p PATH
-            Provides the config folder path. The default is
-            /home/maxwell/Dokumente/github/docker-mailserver/config/
-
-    SELinux
-        -z
-            Allows container access to the bind mount content that is shared among
-            multiple containers on a SELinux-enabled host.
-
-        -Z
-            Allows container access to the bind mount content that is private and
-            unshared with other containers on a SELinux-enabled host.
-
 [SUB]COMMANDS
     COMMAND email :=
         ./setup.sh email add <EMAIL ADDRESS> [<PASSWORD>]
@@ -122,6 +96,28 @@ EXAMPLES
         This will provide you with a detailed explanation on how to use the 
         config dkim command, showing what arguments can be passed and what they do.
 
+OPTIONS
+    Config path, container or image adjustments
+        -i IMAGE_NAME
+            Provides the name of the docker-mailserver image. The default value is
+            docker.io/mailserver/docker-mailserver:latest
+
+        -c CONTAINER_NAME
+            Provides the name of the running container.
+
+        -p PATH
+            Provides the config folder path to the temporary container 
+            (does not work if docker-mailserver container already exists).
+
+    SELinux
+        -z
+            Allows container access to the bind mount content that is shared among
+            multiple containers on a SELinux-enabled host.
+
+        -Z
+            Allows container access to the bind mount content that is private and
+            unshared with other containers on a SELinux-enabled host.
+
 EXIT STATUS
     Exit status is 0 if the command was successful. If there was an unexpected error, an error
     message is shown describing the error. In case of an error, the script will exit with exit