EMBI data availability

Thanks for the pull request! I checked that the revised version of the example code with new country code and dataset code works fine in Julia with DBS dataset.

However, one thing I just found is that the fetching code for WDI part of WB data has not been revised? For example, you can see that the data series can not be searched for along the frequency dimension in the webpage of WB/WDI | DBnomics.

Maybe this is why I cannot get the data by using a similarly revised code like below?

julia> rdb("WB","WDI", dimensions = (country = ["KOR"], frequency = ["A"], indicator = ["NE.CON.GOVT.ZS"]))
┌ Warning: No data series found.
└ @ DBnomics C:\Users\Min\.julia\packages\DBnomics\otwZO\src\dot_rdb.jl:49

*Update: This issue has been already reported. See WDI and error from frequency code - #2 by cbenz.