The ACL policy examples documented on the Consul Storage Backend and
Consul Service Registration pages are too permissive. Both policies
unnecessarily grant agent:write and node:write access for all agents
within the Consul datacenter. When Consul is used solely for service
registration, `service:write` is only required permission.
This commit modifies the policy for the Consul Storage Backend to
remove node:write access, and changes agent:write to agent:read.
The policy on the Consul Service Registration page is updated to
remove all KV-related privileges, and solely grant the necessary
service:write permission.
* Improve "Integrated Storage" documentation
* add missing markup
* add more links to the configuration pages
* Improve the Raft Storage configuration page
* More markup
* Improve the "High Availability" documentation
* More links to the configuration pages
* More links
* even more links
