Add Sofiaplan to Open Data

[rositca-yancheva]

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[marcelscruz]

Hi @rositca-yancheva, thank you for the contribution.

The URL you added seems to be broken, can you please have a look at it?

[rositca-yancheva]

Ah yes, I added the base URL for the API instead of the URL with its documentation : ) Fixed

[marcelscruz]

Thanks!