Fix contradictions between the documentation, the README, and the library (#5825)

- Discarded values: the legacy macro only changes <= and >=; != is true by default
- Out-of-range numbers are rejected while parsing, not stored as NaN
- merge_diff round trip: point to the ordered_json caveat
- ensure_ascii example shows the escaped output
- out_of_range.405 is thrown for "remove"/"move" on the root, not "add"
- CBOR stores binary subtypes as tags
- Integer/float comparison uses exact values, not conversion
- diff, flatten, and the binary writers are depth-bounded
- FAQ: max_digits10 for serialization, trailing commas are supported
- out_of_range.407 is still thrown by to_bon8
- FetchContent_MakeAvailable needs CMake 3.14
- json_fwd.hpp contents, operator< link, RFC 7396 for merge patch
- README: dump() wording, merge_diff, MSYS2/build2, patch comment typos,
  operator[] link, embedded CMake example aligned with the docs

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

docs/mkdocs/docs/features/binary_values.md

@@ -267,9 +267,10 @@ unsigned 8-bit integer. If no subtype is given, the generic binary subtype 0x00
 
 ### CBOR
 
-[CBOR](binary_formats/cbor.md) supports binary values, but no subtypes. Subtypes will be serialized as tags. Any binary
-value will be serialized as byte strings. The library will choose the smallest representation using the length of the
-byte array.
+[CBOR](binary_formats/cbor.md) supports binary values and subtypes. Any binary value will be serialized as a byte
+string; a subtype is serialized as a tag preceding it. When parsing, tags are only read back as subtypes with
+`cbor_tag_handler_t::store` (see [`from_cbor`](../api/basic_json/from_cbor.md)). The library will choose the smallest
+representation using the length of the byte array.
 
 ??? example "Example: serialize a binary value to CBOR"