Documentation: test.h - fix warnings

Fix warnings at 'make htmldocs', and formatting issues in the resulting
documentation.

- test.h: Fix annotation in kernel-doc parameter description.

- Documentation/*.rst: Fixing formatting issues, and a duplicate label
  issue due to usage of sphinx.ext.autosectionlabel and identical labels
  within one document (sphinx warning)

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>