Fix index.html file

[Emmanuel-Melon]

I have examined the index.html file and found the following issues.

• Missing div closing tag on line 31 in the navbar section of index.html.
• Extra padding around jumbotron and navbar.
• Missing header element to make HTML more semantic.
• Invalid id references in form input labels.
• Presence of commented code sections.
• Grammatical errors and typos.