Add more platform-specific information and commands.

Change-Id: I54e5e8692b16330bf4d9316eaef0de5c895ec147
Reviewed-by: Marius Storm-Olsen <marius.storm-olsen@nokia.com>

Let the user at least see the license once (but explain
the use of -confirm-license in the Hints section).

Change-Id: I847486e73b3d78c0f4d18562446ec1172d746ff3
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

Advocating -nokia-developer for any 'developer-build' sounds wrong.
Instead use -developer-build .

Change-Id: I8b93bc1222fd2754f8ed120d3bd856a4cd38f88c
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

Change 1fab62b930edd in qtbase removes demos from default build
targets: demos and examples are merged into one in Qt 5.

Change-Id: Idc6577920cb8678efe493898d85553050c752787
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

Explain the stable build process first, followed by the bleeding-edge
build process.  Previously, the README exclusively recommended only the
process for building bleeding-edge of all modules together, which
frequently results in build failures.