[doc] perldata hash slice example will blow up if used for more than depth 1

[jidanni]

perldata says

Since you can assign to a list of variables, you can also assign to an array or hash slice ...

@colors{'red','blue','green'} = (0xff0000, 0x0000ff, 0x00ff00);

The previous assignments are exactly equivalent to ...

($colors{'red'}, $colors{'blue'}, $colors{'green'}) = (0xff0000, 0x0000ff, 0x00ff00);

OK, but it needs to mention more than just one depth,

@{$colors{favorites}}{ 'red', 'blue', 'green' } #OK

Else users will extend the analogy presented, and assume

@colors{favorites}{ 'red', 'blue', 'green' } #syntax error

will work !

Also mention there is no way to use a consistent syntax for first vs.
more layers.