All docs are treated equally in the search results. The built-in search
system knows to emphasize hits in titles and object names, but could use
some help understating hits in non-definitive docs. In particular, hits
to docs in the /boards, /samples, and /reference/kconfig docs are often
not as important as hits in other docs, so let's push them later in the
search result output.
We can tweak the search results scoring (and thereby the order of
display) via the ``html_search_scorer`` setting in ``conf.py`` along
with a piece of JavaScript to adjust the result score.
Fixes: #16935
Signed-off-by: David B. Kinder <david.b.kinder@intel.com>