Beam documentation translated to Spanish

Anyone think it could be interesting to translate Beam documentation to Spanish? I think it could help to increase Beam reach.

I would love helping on such goal, I'm a native Spanish speaker.

Let me know what you think.

Thanks, Ricardo.

Imported from Jira [BEAM-10405](https://issues.apache.org/jira/browse/BEAM-10405). Original Jira may contain additional context.
Reported by: rjbordon.