Update introduction.md
Update introduction.md

Added contributors for Slovenian.
nschneid/docs,PhyloStar/UDTelugu,hamzashafqat/docs,PhyloStar/UDTelugu,fginter/docs,coltekin/docs,fginter/docs-fginterfork,PhyloStar/UDTelugu,fginter/docs,nschneid/docs,nschneid/docs,coltekin/docs,ftyers/docs,ftyers/docs,UniversalDependencies/docs,PhyloStar/UDTelugu,coltekin/docs,UniversalDependencies/docs,ftyers/docs,coltekin/docs,UniversalDependencies/docs,fginter/docs-fginterfork,hamzashafqat/docs,hamzashafqat/docs,hamzashafqat/docs,fginter/docs,nschneid/docs,fginter/docs-fginterfork,fginter/docs,coltekin/docs,UniversalDependencies/docs,fginter/docs-fginterfork,PhyloStar/UDTelugu,fginter/docs,UniversalDependencies/docs,UniversalDependencies/docs,fginter/docs-fginterfork,ftyers/docs,PhyloStar/UDTelugu