Typos and consistency in configuration.rst

This patch set updates the configuration.rst file to:

- Fix a few minor typographical and grammatical errors
- Make case consistent (e.g. "tempest" vs. "Tempest")
- Make style consistent (e.g. make references to config file keywords
  consistently monospace)
- Spell out numbers less than ten
- Fix a couple of minor content issues as suggested by @mtreinish.

No change in meaning or content is intended.

Change-Id: I5a23e2c39c57eec1e6dbc2a5a076b933c930f78e
1 file changed