change fork with clone, and change some message text

[codeinthesky]

change fork with clone, and changed some message and button text to make things a little more understandable.

• i think the current terminology used is a little confusing ( or at least I was confused by the messaging :-) but happy to discuss / have these changes ignored / changed if you don't agree).

I think that when using Xcode 'importing' implies that something is being added to Xcode, instead of snippets being added to the repository.

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I'll also take this chance to say Awesome work with this plugin!!!