update documentation to specify how to run ansible

playbooks/edx-east/tools_jenkins.yml

+# Documentation on updating tools-edx-jenkins: https://openedx.atlassian.net/wiki/display/EdxOps/Updating+tools-edx-jenkins
+
+# Updating or creating a new install of tools_jenkins (will restart Jenkins)
+# ansible-playbook -i tools-edx-jenkins.m.edx.org, tools_jenkins.yml -e@/path/to/secure-config/tools-edx.yml
+
+# Update tools_jenkins with new plugins (will not restart Jenkins):
+# ansible-playbook -i tools-edx-jenkins.m.edx.org, tools_jenkins.yml -e@/path/to/secure-config/tools-edx.yml --tags install:plugins
+
 # Configure an instance with the tool jenkins.
 - name: Configure Jenkins instance(s)
   hosts: all