Merge branch 'json-view/08-view-builder' into json-view/10-view-document

Conflicts in the See also lists of nine basic_json pages, is_discarded.md, and features/index.md, where develop (#5638) and this branch both added entries: kept both. Ran make amalgamate.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/docs/api/basic_json/size.md

@@ -53,6 +53,8 @@ JSON value which is `1` in the case of a string.
 
 ## See also
 
+- [empty](empty.md) checks whether the JSON value has no elements
+- [max_size](max_size.md) returns the maximum possible number of elements
 - [basic_json_view::size](../basic_json_view/size.md) - the same function on a zero-copy view
 
 ## Version history