Fix the documentation on how to use -openssl-linked.

You set the environment /before/ you run configure.

Change-Id: I6954656f892214f41b5f2ec4e3f4926eb5a9e247
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
fix doc references to webkit

we can't derive the doc index paths from QMAKEMODULES, as the mkspecs dir
may not live at the repo's top level.
instead, explicitly announce the repo's top level build dirs in QTREPOS,
and use that accordingly.

Task-number: QTBUG-38862
Change-Id: I643ad2bf63c8fca0ffc44ce3457dbe8a16dcab07
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>