Fix formatting and spelling mistakes in the documentation

Highlights:
  - In `maven-surefire-plugin/src/site/apt/developing.apt.vm`, make sure text is not rendered bold.
  - In `maven-surefire-plugin/src/site/markdown/newerrorsummary.md`, ensure proper formatting of the list at the bottom of the page.
  - In `maven-surefire-plugin/src/site/site.xml`, add link to "Using POJO Tests" example.
  - In `maven-surefire-report-plugin/src/site/fml/faq.fml`, mention that upgrading Surefire will resolve the listed known issue.
  - Settle on a consistent title casing for (sub)headings.
  - Synchronize page titles with window titles and menu titles, where sensible.
  - Fix/make consistent italic/bold/monospace typesetting of various terms.