Add Java implementation links to metric model docs.
Add Java implementation links to metric model docs.

Change-Id: If2a36aa305a0806ffdf490f78e85afb71da8c202

wndhydrnt/prometheus,wrouesnel/prometheus,cit-lab/prometheus,Stackdriver/stackdriver-prometheus,flier/prometheus,datajet-io/prometheus,laushinka/prometheus,gesellix/prometheus,abhishekamralkar/prometheus,keegancsmith/prometheus,adamron1/prometheus,brancz/prometheus,SaltedMan/prometheus-annotated,ton31337/prometheus,gcnonato/prometheus,adamron1/prometheus,wrouesnel/prometheus,amorken/prometheus,iksaif/prometheus,Colstuwjx/prometheus,AlekSi/prometheus,fabric8io/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,dln/prometheus,q3k/prometheus,SaltedMan/prometheus-annotated,mrwacky42/prometheus,justintung/prometheus,smyrman/prometheus,amorken/prometheus,datajet-io/prometheus,msiebuhr/prometheus,rajthilakmca/prometheus,datajet-io/prometheus,Conorbro/prometheus,agaoglu/prometheus,PrFalken/prometheus,GoogleCloudPlatform/prometheus,gottwald/prometheus,ton31337/prometheus,gottwald/prometheus,brancz/prometheus,fabxc/prometheus,prasincs/prometheus,PrFalken/prometheus,Conorbro/prometheus,AlekSi/prometheus,laushinka/prometheus,prometheus/prometheus,mtanda/prometheus,JavierZunzunegui/prometheus,hustbill/prometheus,dsymonds/prometheus,rajthilakmca/prometheus,iksaif/prometheus,GoogleCloudPlatform/prometheus,Gouthamve/prometheus,brian-brazil/prometheus,dpatel06/prometheus,eliothedeman/prometheus,abhishekamralkar/prometheus,Colstuwjx/prometheus,msiebuhr/prometheus,gcnonato/prometheus,PrFalken/prometheus,msiebuhr/prometheus,thachmai/prometheus,mtanda/prometheus,dln/prometheus,jmcfarlane/prometheus,Dieterbe/prometheus,dln/prometheus,dmilstein/prometheus,sudhi-vm/prometheus,wndhydrnt/prometheus,RobertKielty/prometheus,wrouesnel/prometheus,trigrass2/prometheus,nicr9/prometheus,amorken/prometheus,slok/prometheus,agaoglu/prometheus,cit-lab/prometheus,JavierZunzunegui/prometheus,kangwoo/prometheus,RobertKielty/prometheus,robbiet480/prometheus,smyrman/prometheus,bluecmd/prometheus,prometheus/prometheus,fabxc/prometheus,Conorbro/prometheus,gcnonato/prometheus,dpatel06/prometheus,robbiet480/prometheus,jmcfarlane/prometheus,keegancsmith/prometheus,Stackdriver/stackdriver-prometheus,sudhi-vm/prometheus,AlekSi/prometheus,kzittritsch/prometheus,ton31337/prometheus,flier/prometheus,amorken/prometheus,brancz/prometheus,dsymonds/prometheus,gesellix/prometheus,bluecmd/prometheus,tomwilkie/prometheus,tattsun/prometheus,prometheus/prometheus,abhishekamralkar/prometheus,jmcfarlane/prometheus,dmilstein/prometheus,prasincs/prometheus,Colstuwjx/prometheus,alileza/prometheus,fabric8io/prometheus,fabxc/prometheus,slok/prometheus,SaltedMan/prometheus-annotated,datajet-io/prometheus,prometheus/prometheus,jbdalido/prometheus,q3k/prometheus,justintung/prometheus,Stackdriver/stackdriver-prometheus,RobertKielty/prometheus,abhishekamralkar/prometheus,jimmidyson/prometheus,justintung/prometheus,dln/prometheus,slok/prometheus,SaltedMan/prometheus-annotated,wxdublin/prometheus,jimmidyson/prometheus,kzittritsch/prometheus,kzittritsch/prometheus,brancz/prometheus,gesellix/prometheus,keegancsmith/prometheus,nicr9/prometheus,Dieterbe/prometheus,cit-lab/prometheus,tomwilkie/prometheus,robbiet480/prometheus,kangwoo/prometheus,mtanda/prometheus,gottwald/prometheus,mrwacky42/prometheus,q3k/prometheus,yanghongkjxy/prometheus,alileza/prometheus,keegancsmith/prometheus,thachmai/prometheus,agaoglu/prometheus,bluecmd/prometheus,hustbill/prometheus,dalanlan/prometheus,kangwoo/prometheus,hustbill/prometheus,tattsun/prometheus,RobertKielty/prometheus,prasincs/prometheus,dpatel06/prometheus,PrFalken/prometheus,jmcfarlane/prometheus,thachmai/prometheus,kangwoo/prometheus,alileza/prometheus,tattsun/prometheus,bluecmd/prometheus,Conorbro/prometheus,JavierZunzunegui/prometheus,GoogleCloudPlatform/prometheus,mrwacky42/prometheus,nicr9/prometheus,agaoglu/prometheus,hustbill/prometheus,yanghongkjxy/prometheus,dalanlan/prometheus,robbiet480/prometheus,rajthilakmca/prometheus,yanghongkjxy/prometheus,cit-lab/prometheus,alileza/prometheus,laushinka/prometheus,wxdublin/prometheus,q3k/prometheus,iksaif/prometheus,dmilstein/prometheus,jbdalido/prometheus,keegancsmith/prometheus,fabric8io/prometheus,trigrass2/prometheus,msiebuhr/prometheus,eliothedeman/prometheus,rajthilakmca/prometheus,Gouthamve/prometheus,jbdalido/prometheus,mtanda/prometheus,brian-brazil/prometheus,jimmidyson/prometheus,eliothedeman/prometheus,smyrman/prometheus,jbdalido/prometheus,kzittritsch/prometheus,gcnonato/prometheus,dsymonds/prometheus,tomwilkie/prometheus,Gouthamve/prometheus,trigrass2/prometheus,slok/prometheus,brian-brazil/prometheus,yanghongkjxy/prometheus,Dieterbe/prometheus,JavierZunzunegui/prometheus,wrouesnel/prometheus,dsymonds/prometheus,GoogleCloudPlatform/prometheus,adamron1/prometheus,gottwald/prometheus,laushinka/prometheus,wndhydrnt/prometheus,AlekSi/prometheus,fabxc/prometheus,Gouthamve/prometheus,justintung/prometheus,eliothedeman/prometheus,iksaif/prometheus,fabric8io/prometheus,smyrman/prometheus,flier/prometheus,trigrass2/prometheus,sudhi-vm/prometheus,Stackdriver/stackdriver-prometheus,wxdublin/prometheus,thachmai/prometheus,gesellix/prometheus,tomwilkie/prometheus,Colstuwjx/prometheus,prasincs/prometheus,ton31337/prometheus,dmilstein/prometheus,dalanlan/prometheus,alileza/prometheus,adamron1/prometheus,sudhi-vm/prometheus,tattsun/prometheus