Added a source-download pointer for decNumber.
Added a source-download pointer for decNumber.

To help document decNumber's origin, I've added a link to the
download section of the decNumber website.

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