Unused file Settings.html removed

[neeraj3029]

Fixes #476

Checklist

• [x] I have read the Contribution & Best practices Guide and my PR follows them.
• [x] My branch is up-to-date with the Upstream master branch.
• [ ] The unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)
• [ ] All the functions created/modified in this PR contain relevant docstrings.

Short description of what this resolves:

Settings.html file is unused here. All functions of Settings page are served by options.html file. The contents of the Settings.html file are that of susi_firefoxbot.

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[neeraj3029]

@rajvaibhavdubey That's a nice suggestion, but as mentioned in PR comment there is already one file dedicated for settings, i.e. options.html file. We can add settings to that. Also, the current Settings.html file is a duplicate of Settings.html file of firefoxbot which has no relevance here.

[neeraj3029]

@ms10398 Please review!