\[[!meta field="value" param="value" param="value"]]
The first form sets a given field to a given value, while the second form
-also specifies some additional sub-parameters.
+also specifies some additional sub-parameters. You can have only one field
+per `meta` directive, use more directives if you want to specify more fields.
The field values are treated as HTML entity-escaped text, so you can include
a quote in the text by writing `"` and so on.