Fix ActiveRecord::AttributeMethods::Dirty documentation [ci skip]

Previously the documentation for the newly introduced (in 5.1) AR::Dirty
methods was misleading, as it stated the the new methods were aliases
for the old methods. This was false, and caused confusion when the
differences in their implementation became apparent.

This change attempts to describe the behaviour of these methods more
accurately, also noting when they are likely to be useful (i.e. before
or after saving a record).

This change also makes minor updates to consistently format the
documentation of this API, in accordance with the API Documentation
Guidelines.

0 files changed, 0 insertions, 0 deletions