Updated bdldfp package doc to acknowledge uint128
Updated bdldfp package doc to acknowledge uint128

The 'Uint128' type provides a component that is used by Decimal
Floating Point components to manipulate 128-bit blocks.  Package
doc is updated to note its existence.

abeels/bde,saxena84/bde,bloomberg/bde-allocator-benchmarks,mversche/bde,saxena84/bde,abeels/bde,bloomberg/bde,saxena84/bde,gbleaney/Allocator-Benchmarks,che2/bde,jmptrader/bde,che2/bde,frutiger/bde,osubboo/bde,jmptrader/bde,abeels/bde,saxena84/bde,minhlongdo/bde,abeels/bde,RMGiroux/bde-allocator-benchmarks,abeels/bde,bowlofstew/bde,bloomberg/bde,RMGiroux/bde-allocator-benchmarks,mversche/bde,minhlongdo/bde,gbleaney/Allocator-Benchmarks,che2/bde,apaprocki/bde,bloomberg/bde,che2/bde,dbremner/bde,bloomberg/bde-allocator-benchmarks,minhlongdo/bde,dharesign/bde,osubboo/bde,minhlongdo/bde,bowlofstew/bde,dbremner/bde,bloomberg/bde,mversche/bde,frutiger/bde,bloomberg/bde-allocator-benchmarks,apaprocki/bde,idispatch/bde,bowlofstew/bde,jmptrader/bde,bowlofstew/bde,jmptrader/bde,osubboo/bde,frutiger/bde,dharesign/bde,RMGiroux/bde-allocator-benchmarks,idispatch/bde,dharesign/bde,apaprocki/bde,apaprocki/bde,dbremner/bde,bloomberg/bde,gbleaney/Allocator-Benchmarks,gbleaney/Allocator-Benchmarks,idispatch/bde,RMGiroux/bde-allocator-benchmarks,dbremner/bde,dharesign/bde,osubboo/bde,RMGiroux/bde-allocator-benchmarks,idispatch/bde,bloomberg/bde-allocator-benchmarks,abeels/bde,mversche/bde,apaprocki/bde,bloomberg/bde-allocator-benchmarks,frutiger/bde