Fix minor points on the Cpp page

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Fix wording

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Restore build system on the main developers documentation index

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Merge pull request #833 from sbesson/rebased/develop/build_system

Restore build system on the main developers documentation index (rebased onto develop)
Merge pull request #832 from sbesson/rebased/develop/dev_tidying_2

Fix minor points on the Cpp page (rebased onto develop)