add a readme, describing hw to run the api-server,

as well as links to further information about other used tools

api-server/README.md

+# API-Server for the Data Catalog
+
+This is the API-server for the Data Catalog, which will provide the backend functionality.
+
+It is implemented via [fastAPI](https://fastapi.tiangolo.com/) and provides an api documentation via openAPI.
+
+For deployment via [docker](https://www.docker.com/), a docker image is included. 
+
+## API Documentation
+
+If the api-server is running, you can see the documentation at `<server-url>/docs` or `<server-url>/redoc`.
+
+
+## Running without docker
+First ensure that your python version is 3.6 or newer.
+
+Then, if they are not yet installed on your machine, install the following two packages via pip:
+
+```bash
+pip install fastapi
+pip install uvicorn[standard]
+```
+
+To start the server, run
+```bash
+uvicorn api-server:app --reload
+```
+
+Withour any other options, this starts your server on `<localhost:8000>`.
+The `--reload` option ensures, that any changes to the `api-server.py` will cause an immediate reload of the server, which es especially interesting during development. If this is not required, just don't include the option.
+
+More information about uvicorn settings (including information about how to bind to other network interfaces or ports) can be found [here](https://www.uvicorn.org/settings/).
+
+
+## Using the docker image
+
+### Building the docker image
+
+To build the docker image of the current version, simply run
+
+```bash
+docker built -t datacatalog-apiserver .
+```
+while in the same directory as the Dockerfile.
+
+ `datacatalog-apiserver` is a local tag to identify the built docker image.
+
+### Running the docker image
+
+To run the docker image in a local container, run 
+```bash
+docker run -d --name <container name> -p localhost:<local_port>:80 datacalog-apiserver
+```
+
+`<container name>` is the name of your container, that can be used to refer to it with other docker commands.
+
+`<local_port>` is the port of your local machine, which will be forwarded to the docker container. For example, if it is set to `8080`, you will be able to reach the api-server at http://localhost:8080.
+
+### Stopping the docker image
+
+To stop the docker image, run
+```bash
+docker stop <container name>
+```
+
+Note, that this will only stop the container, and not delete it fully. To do that, run
+
+```bash
+docker rm <container name>
+```
+
+For more information about docker, please see the [docker docs](https://docs.docker.com)
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