The _Important Elasticsearch configuration_ docs lists a number of items
that you should consider before moving to production. Today this list
does not include configuring snapshots, even though they're very
important to have in production. This commit addresses that omission,
removes some repetition from the introductory paragraphs, and notes that
this config is handled for you on Cloud.
Co-authored-by: James Rodewig <40268737+jrodewig@users.noreply.github.com>