Improve Chronos documentation
Link to extra docs from README, fix typo, describe scaling down
Review feedback
Merge remote-tracking branch 'origin/dev' into api-docs
Fix typo
Merge remote-tracking branch 'origin/api-docs' into api-docs
More liberal use of backticks
Merge pull request #4 from Metaswitch/api-docs

[Reviewer: Andy] API and clustering docs