Cleanup API Guide
Cleanup API Guide

* use code-block markup
* adjust code-block indent
* fix OS_TENANT_NAME environment variable name

Change-Id: Ibbba18d14f81b4c39fecfcbcea9e17498d5e8fe3

openstack/api-site,Tesora/tesora-api-site,Tesora/tesora-api-site,Tesora/tesora-api-site,dreamhost/api-site,Tesora/tesora-api-site,dreamhost/api-site,openstack/api-site,dreamhost/api-site,dreamhost/api-site,Tesora/tesora-api-site,Tesora/tesora-api-site,dreamhost/api-site,dreamhost/api-site,Tesora/tesora-api-site,openstack/api-site,dreamhost/api-site,openstack/api-site