Tag Alias: yoghurt -> yogurt

Aliasing yoghurt -> yogurt.

Reason: Alternate spellings.

I didn't even know "yoghurt" was an alternate spelling, but now I can thank Wikipedia for enlightening me. Doesn't matter which one to me, but it should probably be aliased to keep tag use consistent.

Both tags seem too underused right now to really need an alias between the two.

I'd go with consolidating them under the yogurt tag for now by editing the two images with the yoghurt tag to yogurt.

Created yoghurt -> yogurt.