Add full_refresh config information to incremental model docs

[graciegoheen]

Contributions

• I have read the contribution docs, and understand what's expected of me.

Link to the page on docs.getdbt.com requiring updates

https://docs.getdbt.com/docs/build/incremental-models

What part(s) of the page would you like to see updated?

In the section, "How do I rebuild an incremental model?" I think we should include information about the full_refresh config which can be used to optionally set a resource to always or never full-refresh.

Right now, this config is a bit hidden as it's not tied to the incremental models page.

Additional information

No response