Update environment variable doc * update heading - variables not all set by DEA * add info about MEMORY_LIMIT var subject to space/org quotas * add note for repeated var definitions in VCAP_APPLICATION JSON table
Update environment variable doc
* update heading - variables not all set by DEA
* add info about MEMORY_LIMIT var subject to space/org quotas
* add note for repeated var definitions in VCAP_APPLICATION JSON table

cloudfoundry/docs-dev-guide,bridgetkromhout/docs-dev-guide,logit-io/docs-dev-guide,summerzhao/docs-dev-guide,krujos/docs-dev-guide,cwest/docs-dev-guide,shalako/docs-dev-guide