devcontainer.json for this site

[devopstoday11]

@tfsumon
I need devcontainer.json for both of our hugo based sites (website and docs site) to make development life easy and to keep the testing dependencies same for everyone.
Here are the references for devcontainer.json usage -
https://code.visualstudio.com/docs/devcontainers/create-dev-container#:~:text=The%20dev%20container%20configuration%20is,the%20root%20of%20your%20project.

https://github.com/microsoft/vscode-dev-containers/tree/main/containers/hugo

https://github.com/microsoft/vscode-dev-containers/blob/main/containers/hugo/README.md

https://github.com/microsoft/vscode-dev-containers/blob/main/containers/hugo/.devcontainer/devcontainer.json

https://www.trollcode.no/blog/2019-09-19-hugo-dev-container/

this is very good example which shows how to use devcontainer.json - https://aarynsmith.com/posts/hugo-vscode-docker/

[tfsumon]

Added. Check this PR - #86

[devopstoday11]

merged #86 to my chandu branch