Reintroduce deleted anchor in configuration.md.
Reintroduce deleted anchor in configuration.md.

This anchor was deleted by https://reviews.apache.org/r/42939
but is still referenced by sandbox.md.

Review: https://reviews.apache.org/r/44179/

andschwa/mesos,gsantovena/mesos,kaysoky/mesos,abudnik/mesos,kaysoky/mesos,asamerh4/mesos,reneploetz/mesos,dforsyth/mesos,chhsia0/mesos,gsantovena/mesos,reneploetz/mesos,asamerh4/mesos,chhsia0/mesos,asamerh4/mesos,zmalik/mesos,Gilbert88/mesos,jpeach/mesos,abudnik/mesos,neilconway/mesos,dforsyth/mesos,dforsyth/mesos,chhsia0/mesos,zmalik/mesos,asamerh4/mesos,zmalik/mesos,andschwa/mesos,jpeach/mesos,gsantovena/mesos,gsantovena/mesos,dforsyth/mesos,craimbert/mesos,abudnik/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,verizonlabs/mesos,Gilbert88/mesos,reneploetz/mesos,reneploetz/mesos,gsantovena/mesos,neilconway/mesos,Gilbert88/mesos,neilconway/mesos,kaysoky/mesos,verizonlabs/mesos,craimbert/mesos,chhsia0/mesos,verizonlabs/mesos,jpeach/mesos,gsantovena/mesos,kaysoky/mesos,zmalik/mesos,asamerh4/mesos,zmalik/mesos,craimbert/mesos,kaysoky/mesos,chhsia0/mesos,neilconway/mesos,yuquanshan/customizedMesos,craimbert/mesos,jpeach/mesos,asamerh4/mesos,yuquanshan/customizedMesos,andschwa/mesos,craimbert/mesos,Gilbert88/mesos,abudnik/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,gsantovena/mesos,andschwa/mesos,Gilbert88/mesos,abudnik/mesos,verizonlabs/mesos,andschwa/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,abudnik/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,craimbert/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,verizonlabs/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,jpeach/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,kaysoky/mesos,reneploetz/mesos,Gilbert88/mesos,reneploetz/mesos,jpeach/mesos,zmalik/mesos,zmalik/mesos,reneploetz/mesos,Gilbert88/mesos,andschwa/mesos,jpeach/mesos,craimbert/mesos,asamerh4/mesos,neilconway/mesos,dforsyth/mesos,neilconway/mesos,dforsyth/mesos