feat(doc): Add docker docs

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

docs/content/dev/docker.md

@@ -0,0 +1,19 @@
+# Build
+
+To build docker images of the backend or frontend use the following commands.
+Make sure that you have installed the [Docker BuildKit Plugin](https://docs.docker.com/build/install-buildx/) and
+execute the commands from the root level of the project.
+Otherwise, the build process may fail.
+
+```sh
+docker buildx build -f backend/docker/Dockerfile -t hedgedoc-backend .
+```
+
+or
+
+```sh
+docker buildx build -f frontend/docker/Dockerfile -t hedgedoc-frontend .
+```
+
+
+