Employ consistent typesetting/formatting

Well, typesetting/formatting surely belongs to the "peanuts" of life. This issue is a small attempt to raise sensibility for this topic.

The attached patch contains various minor (mostly typographic) changes intended to improve readability/consistency of the documentation. Some of the rules I chose to follow are surely controversial and a matter of taste:

• Hyperlinks should be readable/understandable without their surrounding context (a best practice for web design, e.g. see Stanford Online Accessibility Program)
• Headline style capitalization for page/section titles (see also Capitalization of Headings and Titles)
• Double quotation marks instead of single quots for quoted text (Quotation Marks and Direct Quotations)
• Proper casing for acronyms (e.g. POM instead of pom, but scp if one wants to refer to the protocol part of a URL literally)
• Monospaced font for file/path names, URLs, plugin goals, command prompts
• Uppercase first letter for plugin names (it might just be my German habit, but I consider "the Clean Plugin" more understandable than "the clean plugin" since I can realize the reference to a name more quickly)

Indepedently from the patch getting rejected or not, it might by worth to create some guidelines (house-style) that Maven developers can follow for their documentation, similar to the Maven Plugin Documentation Standard and the code formatter style.

@Dennis: I did not re-order the plugin goals in index.apt this time, although I would recommend so. To me, the current order seems quite random, e.g. why is site:site listed after site:deploy when one usually would invoke site:site first? I consider the following order (not optimal but just) more intuitiv as it groups related goals:

• site:site
• site:site-deploy
• site:run
• site:stage
• site:stage-deploy
• site:attach-descriptor