intrinsic.texi (IAND): Clarify argument specifications.

* intrinsic.texi (IAND): Clarify argument specifications.
(IBCLR): Add documentation.
(IBITS): Add documentation.
(IBSET): Add documentation.
(IEOR): Add documentation.
(IERRNO): Add documentation.
(INDEX): Add documentation.
(IOR): Add documentation.
(ISHFT): Add documentation.
(ISHFTC): Add documentation.
(KILL): Add documentation.
(LEN_TRIM): Add documentation.

From-SVN: r120452