Inconsistent template name in README

This is a great plugin—nice and simple.

I think the tag `<video-wrapper>` should be renamed to `<VueVideoWrapper>` or `<vue-video-wrapper>` by default. 

I didn't notice that there was an option to rename the tag with the `componentId` option, but I think that should be off by default in the example to avoid confusing newbies.

Thanks!