Slight change to prefetch documentation

[Relequestual]

Added some calrification to the documentation on the prefetch attribute. It was unclear to me at first glance how it was different from join. The additional information explicityly explains without the expectation of knowing about all the other functions.

[Relequestual]

Why would that happen? (Tests failed)

[ribasushi]

Why would that happen? (Tests failed)

As can be seen in the build log:

# Failed test 'No incorrect line endings in 'lib/DBIx/Class/ResultSet.pm' on line 4363: [\s] '
# at /home/travis/perl5/perlbrew/perls/5.18/lib/site_perl/5.18.2/Test/EOL.pm line 144.
# Problem Lines:
# line 4363: [\s] : While[\s]the[\s]L<join>[\s]attribute[\s]will[\s]join[\s]a[\s]table[\s]without[\s]including[\s]the[\s]tables[\s]
# Looks like you failed 1 test of 1334.

In any case - don't worry about it, I will fix it when I review tomorrow

[ribasushi]

I want to try to retain the "reference manual" spirit, and leave the first sentence intact. Please see if this formatting remains readable from your PoV:

...
This attribute is a shorthand for specifying a L</join> spec, adding all
columns from the joined related sources as L</+columns> and setting
L</collapse> to a true value. It can be thought of as a rough B<superset>
of the L</join> attribute.

For example, the following two queries are equivalent:
...

[Relequestual]

I see your point. That does make it clearer. I don't have so much of a problem understanding it now, but I don't know if thats because I've used it more now or not.

[ribasushi]

Ok, closing this for the time being via 556e90d. If you get another round of looking at this and perhaps proposing a better wording keeping the above in mind - it'll be much much appreciated.