Update doc/sphinx/language/gallina-specification-language.rst

Co-Authored-By: Gaëtan Gilbert <gaetan.gilbert@skyskimmer.net>

doc/sphinx/language/gallina-specification-language.rst

@@ -766,7 +766,7 @@ Simple inductive types
       The types of the constructors have to satisfy a *positivity condition*
       (see Section :ref:`positivity`). This condition ensures the soundness of
       the inductive definition. The positivity checking can be disabled using
-      the command :flag:`Positivity Checking` (see :ref:`controlling-typing-flags`).
+      the option :flag:`Positivity Checking` (see :ref:`controlling-typing-flags`).
 
    .. exn:: The conclusion of @type is not valid; it must be built from @ident.