To conform to documentation best practices add a
spellchecker. A Sphinx extension is used.
Correct any current spelling mistakes across the
doc set.
Add a seeding file that extends the system dictionary.
Going forward, the 'spelling_words.txt' file will
be used to extend the dictionary.
Do not enforce spelling during a normal doc build; add
a new tox target.
Add a non-voting Zuul job that consumes the new tox
target.
The doc-contrib documentation will include information
on the spellchecker in a subsequent PR.
Future work is necessary in terms of making checking more
intelligent. As such, file 'dubious_words.txt' has been
added to temporarily store those words that should be
filtered. For instance, the word 'tis' is in this file
because it is part of proper noun 'tpm-tis'. Hyphenated
words (or words in single quotes) could be exempt from
the check.
Change-Id: I70a1d5208b97923c081b359af3208f4de65eb6ca
eb1e9e207b