Documentation: add examples of queries made using XPATH

[ngirard]

Unless I missed something, the documentation doesn't explain how to query document metadata (searching "site:montferret.dev metadata" through Google returned nothing, neither did grepping the source code).

As an example, I tried to query the og:url metadata.
I tried variations of //meta[property='og:url']::attr(content), with or without the leading //, and with or without the attr(content), but was unsuccessful.

Cheers

[ziflex]

Try to use XPATH function for that.

[ngirard]

Thank you for your help !
It might be worth adding examples of queries made using XPATH in the docs, IMHO.
Feel free to close this issue whenever you want.

[suntong]

Yeah, examples of queries made using XPATH would be super, whether in the doc or the cookbook.