Update readme.md; Remove references to docker container

readme.md

@@ -89,21 +89,6 @@ a HTML document, or a PDF document, depending on the file name.
     Markdown files ending on `*-page.md` are translated into corresponding HTML
     or PDF documents.
 
-### Docker container
-
-We provide prebuild docker containers. You may use them in a directory to build
-the html slides with
-
-    docker run --rm -it -v `pwd`:/decker -p 8888:8888 gitlab2.informatik.uni-wuerzburg.de:4567/decker/decker html
-
-or for Windows
-
-    docker run --rm -it -v %cd%:/decker -p 8888:8888 gitlab2.informatik.uni-wuerzburg.de:4567/decker/decker html
-
-Exchange the `html` at the end of the command with your *decker* command of
-choice. Beware that file updates are not propagated into the container so
-`decker server` will not auto refresh.
-
 ## *decker* targets
 
 -   `decker version`