Some documentation changes

Changed Slow control shift register to have optional reset before shifting data.
( Still at least one bug - doesn't store data shifted out of MAROC correctly )

Added register stages to risingEdgeDetect




git-svn-id: https://svn2.phy.bris.ac.uk/svn/uob-hep-pc049a/trunk@35 e1591323-3689-4d5a-aa31-d1a7cbdc5706