Qt for Symbian documentation is ambiguous w.r.t. RVCT versions supported

requirements-symbian.html states "Building Qt libraries requires RVCT 2.2 [build 686] or later ...". This is ambiguous - it could be read as meaning that RVCT4 is supported, which it is not true at present.

To clarify this sentence, we need to make it clear that the "or later" refers to the patch number (686), and not to the major/minor version (2.2).