docs for pipeline out of date

[maiermic]

The examples are out of date and not working, since the signature (i.e. argument names) has changed, e.g.

# Trigger specific Pipeline on a specific revision of the master branch
r.pipelines.trigger(revision="<40-char hash>", name="style-check")

See https://atlassian-python-api.readthedocs.io/bitbucket.html#pipelines-management

[gonchik]

@maiermic I will be happy if you double check pipeline and send PR to fix it