Inject templates for ASR datasets
Wait until #2567 is merged so we can benefit from the tagger :) thanks for the feedback @lhoestq! i've added the new language codes and this PR should be ready for a merge :)
This PR adds ASR templates for 5 of the most common speech datasets on the Hub, where "common" is defined by the number of models trained on them.

I also fixed a bunch of the tags in the READMEs 😎 