Improve documentation: byte layouts, release pages, See also, dark-mode images (#5906)

- Make the iterator range illustrations legible in dark mode (prefers-color-scheme
  rules inside the SVGs).
- Add a "Byte layout" section with a color-coded byte table to each binary format
  page (BJData, BON8, BSON, CBOR, MessagePack, UBJSON), and highlight the smallest
  size per file in the comparison table.
- Add "See also" sections to the overview pages that lacked one.
- Split the release notes into one page per release, grouped by minor version on
  the overview page, with an "API changes" section per release generated from the
  API pages' version histories (hooks/api_changes.py).
- Fact-check the release notes and version histories against the release tags and
  correct wrong or misleading entries (e.g., json_serializer 2.1.0, merge_patch
  3.1.0, items, count, operator[], to_bjdata, std::string_view key support).

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

docs/mkdocs/docs/api/basic_json/value.md

@@ -231,11 +231,8 @@ changes to any JSON value.
 1. Added in version 1.0.0. Changed parameter `default_value` type from `const ValueType&` to `ValueType&&` in version
    3.11.0. Deleted overload for integral key types added in version 3.13.0 to reject such calls at compile time
    instead of causing undefined behavior at runtime.
-2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Fixed in version 3.13.0
-   to consistently accept `std::string_view`-convertible keys, as already supported by
-   [`operator[]`](operator[].md), [`at`](at.md), [`find`](find.md), and other lookup functions.
-3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0, including fixing an issue where resolving
-   `ptr` through an array unexpectedly threw `out_of_range` instead of returning the resolved element (or
-   `default_value`, as documented). Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
+2. Added in version 3.11.0. Made `ValueType` the first template parameter in version 3.11.2. Support for keys
+   convertible to `std::string_view` added in version 3.13.0, consistently across the lookup functions.
+3. Added in version 2.0.2. Extended to work with arrays in version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109)
    instead of returning `default_value` for a one-character array index that is not a digit (e.g., `/x`) in version
    3.13.0, as it already did for longer ones.