Make breadcrumbs consistent with .NET and ASP.NET docs

[scottaddie]

Fixes #2131

Internal review page

This PR also updates the master ToC by:

• Removing gerunds, where it makes sense
• Convert titles to sentence case

[ajcvickers]

Thanks for doing this, @scottaddie :-)

[scottaddie]

@smitpatel @ajcvickers I have a bit more testing to do, but so far everything looks good. Hold off on merging for now.

[scottaddie]

@smitpatel @ajcvickers Ready for one last review. You can use the following link to preview the changes:

https://review.docs.microsoft.com/ef/core/?branch=pr-en-us-2159

[smitpatel]

Looks good.

[smitpatel]

A related weird thing. @ajcvickers can define behavior

https://review.docs.microsoft.com/en-us/ef/core/miscellaneous/testing/sqlite?branch=pr-en-us-2159
When clicking on fundamentals in breadcrumbs, it takes to connection strings page since there is no overview page for fundamentals. Should we make this experience somewhat better? How?

[scottaddie]

@smitpatel The preferred approach is to create an Overview page within the Fundamentals node. That doesn't exist, so I have it link to the Connection Strings doc instead.

[ajcvickers]

I think it's fine for now. But we should create an Overview page at some point. Filed #2160