Several QoL (quality of life) improvements

[embeddedt]

Proposed Changes

• Change hover color to be distinct from selection
  • See commit message.
• Explicitly state when no option is selected on voting page
  • so students know if their selection has not been processed server-side.
• Send a browser notification when a new question starts
  • I often switch away from my browser window; this will send a notification that should be visible even if the browser isn't.
• Fix a typo in the README

Tests

Please describe the tests that you ran to verify your changes.

• [x] Verified that selection still shows the same color
• [x] Verified that hovering has significant contrast from not hovering
• [x] Ran a local poll and verified that a notification is sent when a new question starts
• [x] Ran a local poll and verified that "Selected Option: None" is shown initially, instead of "Selected Option:"
• [x] Tested on Edge for Windows 11 and verified that notifications are displayed consistently, even the second time

[hiimchrislim]

Will be looking at this during the weekend. (A bit busy at work atm)

[huonggiangbui]

@hiimchrislim are you able to check this?

[shubhbapna]

@embeddedt is it possible to open the PR against gdsc open source branch. I want to include this in the next release scheduled for first of week of winter

[embeddedt]

I switched the base and the commits seem to still be intact; let me know if I still need to create a new PR.