Update demo.html's bootstrap4 to the current release 4.5.0.

[dcslagel]

Describe the bug docs/demo.html is currently using version 4.0.0-alpha.6. Update to current production level version 4.5.0 so we are using current features for menu development.

To Reproduce Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior demo.html should behave the same as before for all menu items.

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context Add any other context about the problem here.