Correct description of section 15 winds

[nhsavage]

There is an error in metarelate for the diagnostics:

15.201 U WIND ON PRESSURE LEVELS B GRID and
15.202 V WIND ON PRESSURE LEVELS B GRID.

According to the STASHmaster these have a rotate code of 1, "Data is passed to STASH relative to the lat-long grid" and so should have CF names of eastward_wind and northward_wind (whether the model grid has a lat-lon grid or a rotated pole). However in Metarelate these have the names x_wind and y_wind. This is correct for models with a lat-lon grid but incorrect for rotated pole models.

The changes are correct, to the best of my knowledge.
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