Add documentation how to override object equality

[coezbek]

It is unclear to me if (at all) and how to define what constitutes equality for diff-lcs. I tried overriding == operator but this did not work.

Looking into the code it seems Hash equality needs to be implemented (i.e. eql? and hash).

diff-lcs/lib/diff/lcs/internals.rb

Line 294 in e4b0274

def position_hash(enum, interval)

Would it make sense to document this?

[halostatue]

It would be. I’d suggest that it might be worth adding some tests to verify this.