docs: add sql examples for window functions

[spencerscott917]

Which issue does this PR close?

Closes #13399

Rationale for this change

Give users examples of how to use window functions and intuition about how these functions work

What changes are included in this PR?

Examples for each window function are now provided in documentation.

Are these changes tested?

Are there any user-facing changes?

[alamb]

Thank you @spencerscott917 🙏

Since the user documentation is generated, I think you will have to add these examples to get the CI to pass

Here is an example of how to do it https://github.com/apache/datafusion/pull/13390/files

Basically put the markdown you have made into rust and a .with_sql_example(r#

[spencerscott917]

Thank you @spencerscott917 🙏

Since the user documentation is generated, I think you will have to add these examples to get the CI to pass

Here is an example of how to do it https://github.com/apache/datafusion/pull/13390/files

Basically put the markdown you have made into rust and a .with_sql_example(r#

Sounds good, I will give that a go. Thanks for the example to follow @alamb

[alamb]

these are nice

[alamb]

Marking as draft as I think this PR is no longer waiting on feedback. Please mark it as ready for review when it is ready for another look