Apply the review's wording fixes to the json_view documentation

- Copying is disabled because of its cost, not because of two documents
  borrowing the same buffer; the unique_ptr follows from move-only.
- Inputs: streams, FILE*, and wide characters (strings, arrays, pointers)
  are all supported and owned; point to parse_copy() for owned copies.
- The error replay only runs for failing input, builds no values, and is
  skipped with allow_exceptions = false.
- read() writes copied inputs into the previous owned copy.
- Views can dangle like std::string_view, and why there is no
  shared/weak pointer design.
- The 4 GiB limit (16-byte nodes, 16-byte scanner steps), streams being
  read to the end first, which macros apply, why materialize() has no
  source positions, and wording nits (accept() vs basic_json::accept(),
  is_binary, is_discarded, see-also lists, size table, "back into").

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

docs/mkdocs/docs/api/basic_json_document/index.md

@@ -11,13 +11,14 @@ A parsed JSON text, held as a flat index of its values
 ([16 bytes per value](../../home/architecture.md#node-index-of-json-views)) instead of a tree of `BasicJsonType` values.
 Strings and numbers stay in the source text; only strings that contain escapes are decoded, into one buffer owned by
 the document. [`basic_json_view`](../basic_json_view/index.md) is a read-only handle to one value of a
-`basic_json_document`; [`materialize()`](../basic_json_view/materialize.md) turns a subtree back into the
+`basic_json_document`; [`materialize()`](../basic_json_view/materialize.md) turns a subtree into the
 `BasicJsonType` value that [`BasicJsonType::parse()`](../basic_json/parse.md) would have produced for it.
 
 A document may **borrow** the text it was parsed from (the caller's buffer must then outlive the document) or **own**
 it (a copy, or an rvalue `#!cpp std::string` that was moved in); see [`owns_source`](owns_source.md). `basic_json_document`
-is move-only: copying a document would either duplicate a potentially large index and text, or leave two documents
-claiming to borrow the same buffer, so it is disabled.
+is move-only: a copy would duplicate the whole index, the decoded-string buffer, and the owned text, and a move is
+enough in every use we know of. The index, the decoded strings, and the owned text live in one heap block that the
+document holds through a `#!cpp std::unique_ptr`; this is also why views survive a move of the document.
 
 ## Template parameters