Updated README formatting (#10)
Updated README formatting (#10)

* Updated README

Corrected some minor typos.
Added language keywords for syntax highlighting in code blocks.
Added additional markup around keywords (parameters, environment
variables etc).
Editor removed trailing whitespace.
Added markup for replication warning.
Added attachment warning.
Used animaldb for database name and file names, animaldb2 for restored database name

cloudant/couchbackup,cloudant/couchbackup