Adds local documentation server command and integrate version switcher in docs

[medha-14]

[medha-14]

@maharshi-gor @skoudoro When I am on a page other than index.html in the newly built local docs and select a particular version it redirects to that version's index.html instead of the page the user was previously on. Is this behavior intended or do you want me to change it? If that page or docs are not available in the previous version it will redirect to the index page.