Documentation for the spellchecker has been integrated into the
existing l18n documentation available at:

  http://d-i.alioth.debian.org/doc/i18n/

(see "7. Translations spellchecking" chapter)
it consist of information useful mainly to translators and explains
how to use the information produced by the spellchecker in order to
improve the quality of translations.

The "doc" directory consists of notes intended to help people to set
up the spellchecker, not necessarily to check translations of d-i