KLC: document suggested EP pad sizes

[poeschlr]

Document the fact that by default the EP should use the nominal size of the packages "lead".
If the datasheet suggests a differently sized EP then this should be used.

If the suggestion is outside the tolerance ranges then it might be required to check that this is not a mistake in the datasheet. Most packages with significangly larger copper pad compared to lead use soldermask defined pads to increase the copper area (increased thermal transfer)