ReleaseNotes: fix sorting, spotted by Eugene Zelenko

  Adds ``[[nodiscard]]`` attributes (introduced in C++17) to member functions

  to highlight at compile time which return values should not be ignored.

- New :doc:`readability-isolate-decl

  <clang-tidy/checks/readability-isolate-declaration>` check.

  Detects local variable declarations declaring more than one variable and

  tries to refactor the code to one statement per declaration.

- New :doc:`readability-const-return-type

  <clang-tidy/checks/readability-const-return-type>` check.

  Checks for functions with a ``const``-qualified return type and recommends

  removal of the ``const`` keyword.

- New :doc:`readability-isolate-decl

  <clang-tidy/checks/readability-isolate-declaration>` check.

  Detects local variable declarations declaring more than one variable and

  tries to refactor the code to one statement per declaration.

- New :doc:`readability-magic-numbers

  <clang-tidy/checks/readability-magic-numbers>` check.