Add an EXAMPLES section to kyuafile(5)

Move the sample Kyuafile from the beginning of the manual page to a new
EXAMPLES section.  While doing so, tweak the example and add a simpler
code sample.
Clarify include() restrictions in kyuafile(5)

Make it explicitly clear that include() in Kyuafiles cannot refer to
absolute paths and explain why.

Add a new example to describe how a user might connect disjoint test
suites into a single one so that Kyua can run them all together.
Merge branch 'issue-114'

Improve the kyuafile(5) manpage by adding more examples and clarifying
the behavior of include().