put commends back inline to help demonstrate what commands mean

containers/typescript-node-8/.devcontainer/Dockerfile

@@ -7,11 +7,17 @@ FROM node:8
 
 # Configure apt
 ENV DEBIAN_FRONTEND=noninteractive
+
+# Set the default shell to bash instead of sh
 ENV SHELL /bin/bash
 
+
 RUN apt-get update \
     && apt-get -y install --no-install-recommends apt-utils 2>&1 \
-    && apt-get install -y git procps \
+    # Verify git and needed tools are installed
+    && apt-get install -y git procps \    
+    # Remove outdated yarn from /opt and install via package 
+    # so it can be easily updated via apt-get upgrade yarn
     && rm -rf /opt/yarn-* \
     && rm -f /usr/local/bin/yarn \
     && rm -f /usr/local/bin/yarnpkg \
@@ -20,7 +26,9 @@ RUN apt-get update \
     && echo "deb https://dl.yarnpkg.com/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/ stable main" | tee /etc/apt/sources.list.d/yarn.list \
     && apt-get update \
     && apt-get -y install --no-install-recommends yarn \
+    # Install tslint and typescript
     && npm install -g tslint typescript \
+    # Clean up
     && apt-get autoremove -y \
     && apt-get clean -y \
     && rm -rf /var/lib/apt/lists/*