Update docs/extensions/lua-api.qmd

Co-authored-by: Charlotte Wickham <[email protected]>

Author: cscheid

docs/extensions/lua-api.qmd

@@ -293,7 +293,7 @@ function Meta(meta)
 end
 ```
 
-The function returns a `pandoc.MetaValue`, which may be a `MetaString`, `MetaInlines`, `MetaList`, `MetaMap`, or other Pandoc metadata types. You can use `pandoc.utils.stringify()` to convert these to strings when needed:
+The function returns a `pandoc.MetaValue`, which may be a `MetaString`, `MetaInlines`, `MetaList`, `MetaMap`, or other [Pandoc metadata types](https://pandoc.org/lua-filters.html#type-metavalue). You can use `pandoc.utils.stringify()` to convert these to strings when needed:
 
 ``` lua
 function Pandoc(doc)