Document json_document and json_view

- API pages for basic_json_document and basic_json_view, one per member,
  and for the four aliases, each with an example
- features/json_view.md: the problem the view solves, ownership and
  lifetime, what matches basic_json::parse() and what differs, and when
  to choose json, ordered_json, SAX, or the view
- the examples show why one would use the view, not only how: borrowed
  vs. owned input, reading a few fields and materializing one subtree,
  reusing a document across many messages
- registered in the mkdocs navigation, llms.txt, the docset, the
  exceptions page (out_of_range.416), architecture.md, the integration
  page, and the README; the yyjson credit is added to the README and
  license.md

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

docs/mkdocs/docs/home/exceptions.md

@@ -1002,6 +1002,23 @@ MessagePack's ext type and BSON's binary subtype are each stored in a single byt
 
     This exception was added in version 3.13.0. Before that, subtypes above 255 were silently truncated modulo 256 instead of raising an error.
 
+### json.exception.out_of_range.416
+
+[`basic_json_document::parse()`](../api/basic_json_document/parse.md) and the other parsing functions of
+[`basic_json_document`](../api/basic_json_document/index.md) index a value's position in the source text in 32 bits,
+so they do not support an input of 4 GiB or more.
+
+!!! failure "Example message"
+
+    ```
+    [json.exception.out_of_range.416] input of 4 GiB or more is not supported by json_document
+    ```
+
+!!! note
+
+    This exception was added in version 3.13.0, together with [`<nlohmann/json_view.hpp>`](../features/json_view.md).
+    [`basic_json::parse()`](../api/basic_json/parse.md) has no such limit.
+
 ## Further exceptions
 
 This exception is thrown in case of errors that cannot be classified with the