htmldoc: fix source URI
htmldoc: fix source URI

mrsweet.org is not serving the file anymore.

nielx/haikuports,miqlas/haikuports,Begasus/haikuports,haikuports/haikuports,haikuports/haikuports,haikuports/haikuports,moochris/haikuports,Begasus/haikuports,moochris/haikuports,Begasus/haikuports,miqlas/haikuports,haikuports/haikuports,moochris/haikuports,nielx/haikuports,koletzky/haikuports,haikuports/haikuports,koletzky/haikuports,Begasus/haikuports,miqlas/haikuports,nielx/haikuports,Begasus/haikuports,koletzky/haikuports