docs: add examples for spellchecker and spell-checker ignores

[cylewaitforit]

This adds examples for using spellchecker and spell-checker ignores. The PR tries to follow the same format as disables from the section above.

[Jason3S]

@cylewaitforit,

Thank you for the examples.

The docs directory is going to go away. We are moving everything to Docusaurus. Would you add your changes to: https://github.com/streetsidesoftware/cspell/blob/main/website/docs/Configuration/document-settings.md

Thank you.

[Jason3S]

@cylewaitforit,

Thank you.

[cylewaitforit]

@Jason3S Cool, I made changes there as well. I also found another spot that it seemed worth calling out the use of “spellchecker: ”

I like Docusaurus a lot but just out of curiosity did you give any consideration to using Astro Starlight docs instead?