Add basic example to the docs

[oxinabox]

using Embeddings
const embtable = load_embeddings(Word2Vec) # or load_embeddings(FastText_Text) or ...

const get_word_index = Dict(word=>ii for (ii,word) in enumerate(embtable.vocab))

function get_embedding(word)
    ind = get_word_index[word]
    emb = embtable.embeddings[:,ind]
    return emb
end

@show get_embedding("blue")