Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 assertion_lifting_consequent(Arg1, Arg2)

 assertion_lifting(Arg1, Arg2)

 assertion_mt(Arg1, Arg2)

 assertion_content(Arg1, Arg2, Arg3)

 assertion_content(Arg1, Arg2, Arg3, Arg4)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8, Arg9)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8, Arg9, Arg10)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8, Arg9, Arg10, Arg11)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8, Arg9, Arg10, Arg11, Arg12)

 assertion_content(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8, Arg9, Arg10, Arg11, Arg12, Arg13)