added Dockefile and entrypoint.sh

It uses the latest available version for libtorrent and builds both libtorrent and qBittorrent with Cmake + ninja

The legal notice must be accepted trought an environment variable called LEGAL and passed to docker when the container is run, to set it true one must set "LEGAL=accept"

PR #16828.

dist/docker/Readme.md

@@ -0,0 +1,67 @@
+# Docker Container Name
+
+This Dockerfile allows you to build a qBittorrent-nox container
+
+## Getting Started
+
+### Prerequisities
+
+
+In order to run this container you'll need docker installed.
+
+* [Windows](https://docs.docker.com/windows/started)
+* [OS X](https://docs.docker.com/mac/started/)
+* [Linux](https://docs.docker.com/linux/started/)
+
+
+## Built
+
+in the docker folder run
+
+```shell
+release="4.2.0" ; sudo docker build --build-arg BUILD_TYPE=Release --build-arg RELEASE=$release -t qbittorrent-nox:$release --rm  .
+```
+
+where:
+
+* the `release` variable is the specific tagged version you want to build
+* the `BUILD_TYPE` argument is the build you want to create `Debug` or `Release`
+* the `RELEASE` argument works as the but is the actual argument given to docker, in the above script is defined by the `release` variable
+
+
+### Usage
+
+#### Container Variables
+
+there is one important variable to run the container:
+
+* the `LEGAL` varible defines if you accept the Legal Notice, put accept as a value only if you understand and accept the Legal Notice
+
+#### Volumes
+
+there are two main locations:
+
+* `downloads` contains the files downloaded by qBittorrent
+* `config` contains qBittorrent configurations
+
+```shell
+docker run give.example.org/of/your/container:v0.2.1 parameters
+```
+
+#### Network
+
+on the port `8080` the webinterface is run
+
+#### RUN
+
+To start the the docker image simply run
+
+```shell
+docker run --env LEGAL=accept -p 8080:8080 -v /your/path/config:/config -v /your/path/download:/downloads --name qBittorrent qbittorrent-nox:4.2.0
+```
+
+to stop the container
+
+```shell
+docker stop qBittorrent
+```