DOCS: update environment variables page

- Relocate Environment Variables page to Agent section
- Correct front matter newlines issue

website/source/docs/agent/environment-variables.html.markdown

@@ -1,12 +1,9 @@
 ---
 layout: "docs"
 page_title: "Environment Variables"
-sidebar_current: "docs-commands-environment-variables"
+sidebar_current: "docs-agent-envvars"
 description: |-
-  In addition to CLI flags, Consul reads environment variables for behavior
+  In addition to CLI flags, Consul reads environment variables for behavior defaults. CLI flags always take precedence over environment variables, but it is often helpful to use environment variables to configure the Consul agent, particularly with configuration management and init systems.
-defaults. CLI flags always take precedence over environment variables, but it
-is often helpful to use environment variables to configure the Consul agent,
-particularly with configuration management and init systems.
 ---
 
 # Environment Variables

website/source/layouts/docs.erb

@@ -184,6 +184,10 @@
 					<a href="/docs/agent/dns.html">DNS Interface</a>
 					</li>
 
+					<li<%= sidebar_current("docs-agent-envvars") %>>
+					<a href="/docs/agent/environment-variables.html">Environment Variables</a>
+					</li>
+
 					<li<%= sidebar_current("docs-agent-http") %>>
 					<a href="/docs/agent/http.html">HTTP API</a>
 					<ul class="subnav">