[Translation] [Spanish] Jest. (1344 translated words) (Part 1)

Jest is used by Facebook to test all JavaScript code including React applications. One of Jest's philosophies is to provide an integrated "zero-configuration" experience. We observed that when engineers are provided with ready-to-use tools, they end up writing more tests, which in turn results in more stable and healthy code bases. I came across this project in Crowdin and I wanted to aport given that the spanish translating contributions were below 80% complete.