Add vignette

[stitam]

I should add a vignette for the package with a number of use case examples.

For example, I have come across a situation where I had a number of IDs which I assumed to be all protein IDs. 1. it turned out that some were from nuccore, 2. article references were not 100% accurate, 3. sequence data was missing for some of them. I could add simple example on how to generate these using webseq functions i.e. ncbi_get_uid(), ncbi_link_uid(), ncbi_recover_id().

[stitam]

Another use case to add: protein ids > nuccore ids > taxonomy > classification.