Fix default editor in Dev Container

See merge request !577

Co-authored-by: Neil-Jocelyn Schark <neil-jocelyn.schark@stud.h-da.de>

.devcontainer/Dockerfile

@@ -34,8 +34,8 @@ ENV SHELL /bin/zsh
 RUN wget https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | zsh || true
 
 # Set editor
-RUN echo "export VISUAL='nano'" >> .zshrc
-RUN echo "export EDITOR='nano'" >> .zshrc
+RUN echo "export VISUAL='nano'" >> /home/vscode/.zshrc
+RUN echo "export EDITOR='nano'" >> /home/vscode/.zshrc
 
 # Install preferred version of the containerlab
 RUN bash -c "$(curl -sL https://get.containerlab.dev)" -- -v ${_CLAB_VERSION}