Add Additional Spanish Translation

[mjonasftc]

Is your feature request related to a problem? Please describe.
To continue adding Spanish translation strings to the es_ES.po file, I asked a publisher to provide a translation for an untranslated string that already exists in the file.

Describe the solution you'd like
In this file (https://github.com/Automattic/newspack-theme/blob/35174c541b7bdf66108ce13735bd544df28507c8/newspack-theme/languages/es_ES.po) add the translation Para 'obtener mas información %s' to line 987

Describe alternatives you've considered
None

Additional context
This string would affect the text that appears here: https://d.pr/i/9MlXFJ which creates an author block on sponsored posts.