Docs issues in chapter 5 HTTP

The following issues are observed in the chapter 5:

1\. In the code sample shown in section 5.2, the html symbol "<" is not
translated as "<".
Snapshot: HtmlSymbolsNotTranslated.gif
2\. The section 5.3.2 doesn't have any content. It just shows the text TODO.
Snapshot: IncompleteSection.gif
3\. Unlike the other sections, the section 5.7 doesn't show how HTTP Persistent
Connections can be achieved in the JAX-WS clients.
#### Environment
Operating System: All
Platform: All
URL: [https://metro.dev.java.net/guide/](https://metro.dev.java.net/guide/)
#### Affected Versions
[1.3]

Source: [https://github.com/javaee/metro-wsit/issues/997](https://github.com/javaee/metro-wsit/issues/997)
Author: glassfishrobot

Start at the Metro guide URL and inspect chapter 5, especially sections 5.2, 5.3.2, and 5.7. Check the HTML symbol example, replace the TODO-only section with its intended content, and document HTTP persistent connections for JAX-WS clients; done means all three reported gaps are resolved in the rendered guide.

Written by the indexing model from the issue text.