Add UNICEF vaccine tracker

Courtesy de-facto

README.md

@@ -289,6 +289,7 @@ Note that the WHO will generally be unable to make statements that their more pr
 
 * [CovidVax](https://covidvax.org/) is an updated list of COVID-19 vaccines, with information on the companies involved, trials and stages (with links to news and other sources used for the data), and a tracker for how many doses have been administered in each country
 * [COVID19 Vaccine Tracker](https://covid19.trackvaccines.org/) has another comprehensive list of vaccines with information about [vaccine type](https://covid19.trackvaccines.org/how-do-vaccines-work/#types), and the trials, stage and approvals by country
+* [UNICEF COVID-19 Vaccine Market Dashboard](https://www.unicef.org/supply/covid-19-vaccine-market-dashboard) (or [direct link](https://app.powerbi.com/view?r=eyJrIjoiNmE0YjZiNzUtZjk2OS00ZTg4LThlMzMtNTRhNzE0NzA4YmZlIiwidCI6Ijc3NDEwMTk1LTE0ZTEtNGZiOC05MDRiLWFiMTg5MjAyMzY2NyIsImMiOjh9) to the full-screen page) with vaccines by approval state and type, countries where approved, current and projected production capacity per type, amounts purchased per country or other buyer, price ranges, and map of delivered doses
 * [RAPS COVID-19 vaccine tracker](https://www.raps.org/news-and-articles/news-articles/2020/3/covid-19-vaccine-tracker)
 * [Precision Vaccinations - COVID-19 Vaccines](https://www.precisionvaccinations.com/covid-19-vaccines) lists a number of COVID-19 vaccine candidates, divided by clinical stage, with brief description and detail pages for each
 * [Contagion Live](https://www.contagionlive.com/view/the-covid19-live-vaccine-tracker) also has descriptions for a few of the vaccines, divided by stage