feh(1): Fix --limit-{height,width} documentation

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.It Cm -H , --limit-height Ar pixels

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Limit the height of the montage, defaults to 800 pixels.

Limit the height of the montage.

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.It Cm -W , --limit-width Ar pixels

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Limit the width of the montage.

Limit the width of the montage, defaults to 800 pixels.

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.Pp

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If both

.Cm --limit-width No and Cm --limit-height

are specified, the montage will be exactly

.Ar width

pixels wide and up to

.Ar height

pixels high.

.Ar width No x Ar height

pixels in dimensions.

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.It Cm -o , --output Ar file

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