add bundler and bundle install to enable docs build in codespaces

Author: keithamus

.devcontainer/Dockerfile

@@ -4,9 +4,8 @@
 ARG VARIANT="16"
 FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:0-${VARIANT}
 
-# [Optional] Uncomment this section to install additional OS packages.
-# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-#     && apt-get -y install --no-install-recommends <your-package-list-here>
+RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+    && apt-get -y install --no-install-recommends bundler
 
 # [Optional] Uncomment if you want to install an additional version of node using nvm
 # ARG EXTRA_NODE_VERSION=10

.devcontainer/devcontainer.json

@@ -22,7 +22,7 @@
 	// "forwardPorts": [],
 
 	// Use 'postCreateCommand' to run commands after the container is created.
-	// "postCreateCommand": "yarn install",
+	"postCreateCommand": "npm i && cd docs && sudo bundle install",
 
 	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
 	"remoteUser": "node",