DOC minor broken links fix in parallelism docs (#19151)
DOC minor broken links fix in parallelism docs (#19151)

Co-authored-by: Thomas J. Fan <5e8796a332fafc9c261437cd1787ae2709a896a7@gmail.com>
scikit-learn/scikit-learn,shyamalschandra/scikit-learn,shyamalschandra/scikit-learn,saiwing-yeung/scikit-learn,AlexandreAbraham/scikit-learn,shyamalschandra/scikit-learn,saiwing-yeung/scikit-learn,jakirkham/scikit-learn,saiwing-yeung/scikit-learn,ogrisel/scikit-learn,amueller/scikit-learn,vinayak-mehta/scikit-learn,vinayak-mehta/scikit-learn,TomDLT/scikit-learn,scikit-learn/scikit-learn,ivannz/scikit-learn,kevin-intel/scikit-learn,AlexandreAbraham/scikit-learn,glemaitre/scikit-learn,ivannz/scikit-learn,amueller/scikit-learn,manhhomienbienthuy/scikit-learn,anntzer/scikit-learn,glemaitre/scikit-learn,sergeyf/scikit-learn,espg/scikit-learn,anntzer/scikit-learn,espg/scikit-learn,huzq/scikit-learn,huzq/scikit-learn,ogrisel/scikit-learn,ivannz/scikit-learn,jakirkham/scikit-learn,kevin-intel/scikit-learn,manhhomienbienthuy/scikit-learn,TomDLT/scikit-learn,manhhomienbienthuy/scikit-learn,glemaitre/scikit-learn,ogrisel/scikit-learn,anntzer/scikit-learn,kevin-intel/scikit-learn,ivannz/scikit-learn,glemaitre/scikit-learn,betatim/scikit-learn,betatim/scikit-learn,manhhomienbienthuy/scikit-learn,AlexandreAbraham/scikit-learn,scikit-learn/scikit-learn,sergeyf/scikit-learn,espg/scikit-learn,amueller/scikit-learn,amueller/scikit-learn,lesteve/scikit-learn,AlexandreAbraham/scikit-learn,kevin-intel/scikit-learn,TomDLT/scikit-learn,TomDLT/scikit-learn,jakirkham/scikit-learn,shyamalschandra/scikit-learn,sergeyf/scikit-learn,anntzer/scikit-learn,betatim/scikit-learn,saiwing-yeung/scikit-learn,vinayak-mehta/scikit-learn,betatim/scikit-learn,jakirkham/scikit-learn,ogrisel/scikit-learn,lesteve/scikit-learn,scikit-learn/scikit-learn,lesteve/scikit-learn,huzq/scikit-learn,sergeyf/scikit-learn,lesteve/scikit-learn,espg/scikit-learn,vinayak-mehta/scikit-learn,huzq/scikit-learn