Translated '10 Failover and Rollback' into Spanish. Close #340.
Translated '11 Connecting to a ReplicaSet from PyMongo' into Spanish. Close #341.
Translated '12 What happens when...' into Spanish. Close #345.
Minor edits for #340.
Minor edits for #341.
Merge pull request #343 from puentesarrin/issue-340

Translated '10 Failover and Rollback' into Spanish. Close #340.
Merge pull request #344 from puentesarrin/issue-341

Translated '11 Connecting to a ReplicaSet from PyMongo' into Spanish. Close #341.
Minor edits for #345.
Merge pull request #347 from puentesarrin/issue-345

Translated '12 What happens when...' into Spanish. Close #345.