Correct optimization flags documentation

Authored by SantiMunin on Jun 8 2017, 2:03 PM.

Description

Correct optimization flags documentation

In a previous change (commit 4fd6207ec6960c429e6a1bcbe0282f625010f52a),
the users guide was moved from XML to the RST format. This process
introduced a typo: "No -O*-type option specified:" was changed to "-O*"
(which is not correct). This change fixes it.

See result in: https://prnt.sc/fh332n

Fixes ticket Trac #13756.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: Trac #13756

Differential Revision: https://phabricator.haskell.org/D3631