PR sequencing - ref Vietnam and Estonia

[RichardMN]

I think #413 and #417 are about ready to merge. I would suggest that Vietnam (#413) go first and then Estonia (#417) can be merged on top of that.

In early celebration of this, I have regenerated the hex sticker which shows what the logo will look like with Estonia and Vietnam both added:
https://github.com/RichardMN/covidregionaldata/blob/map-making/man/figures/logo.png

(There's probably some cunning way of merging this in later - there appears to be a slight coding error in our hexsticker code, and I am going to put in the lines for re-downloading the naturalearth packages so I don't have to google them every time.)

[seabbs]

Lovely to see some more map coverage (especially outside of Western Europe). Both PRs are looking good and happy with either merge order (not clear which order is better TBH).

😆 yes please do put the package download scripts in as that cannot be fun.

[seabbs]

Should all be merged in now and diffs fixed. Shall we update the map hex just before the next CRAN release?