Fix errors reported by W3C Markup Validator

[hareesh-pillai]

W3C Markup Validator reports the following errors while scanning the website. These errors and warnings should be fixed to output valid HTML.

• Warning: Consider adding a lang attribute to the html start tag to declare the language of this document.
• Error: Start tag seen without seeing a doctype first. Expected <!DOCTYPE html>.
• Error: Bad value https://fonts.googleapis.com/css?family=Open Sans for attribute href on element link: Illegal character in query: space is not allowed.