v6: minor docs fixes (#42385)

v6: minor docs fixes (#42385)

* Adjust toast copy, placeholder, and font var

Update docs and styles: change toast example text to use "accent" wording, mark the default toast placement option as disabled to prevent it being selected as a valid value, and switch the table font variable from --bs-font-monospace to the standardized --bs-font-mono in _content.scss.

* fix typo

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>