Several fixes for index.md (#28632)
Several fixes for index.md (#28632)

I made several fixes for the index file.

I changed the structure of several lines or paragraph to make them sound more natural in Spanish, opposed to a direct translation from English.

I fixed those pages where what seems to be auto translation had translated PHP stataments.

I translated several strings in code, and I fixed at least one bug in the PHP examples (The ending tag of here documents cannot have spaces between the tag and the margin).
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