Add secret text credentials documentation
Add secret text credentials documentation

juliandunn/jenkins,gshively11/jenkins,Sauraus/jenkins,chef-cookbooks/jenkins,daften/cookbook-jenkins,autoclone/jenkins-cookbook,gshively11/jenkins,juliandunn/jenkins,opscode-cookbooks/jenkins,mknapik/jenkins,Dispader/jenkins,b-dean/jenkins,Dispader/jenkins,chef-cookbooks/jenkins,mknapik/jenkins,chef-cookbooks/jenkins,autoclone/jenkins-cookbook,Sauraus/jenkins,b-dean/jenkins,b-dean/jenkins,mknapik/jenkins,juliandunn/jenkins,Dispader/jenkins,opscode-cookbooks/jenkins,dshvedchenko/jenkins,samdunne/jenkins,Sauraus/jenkins,dshvedchenko/jenkins,StephenKing/chef-cookbook-jenkins,StephenKing/chef-cookbook-jenkins,dshvedchenko/jenkins,autoclone/jenkins-cookbook,samdunne/jenkins,StephenKing/chef-cookbook-jenkins,opscode-cookbooks/jenkins,gshively11/jenkins,daften/cookbook-jenkins,samdunne/jenkins,daften/cookbook-jenkins