Checking the whole translation

Started from the bottom and got to "### 2. Prácticas de Open Kanban".
Re-checked whole document - minor corrections

Corrected a few typos. Updated email address of Federico Varchavsky.
Re-written: pull [pull request] to [pedido de pull]
Merge branch 'patch-1' of https://github.com/CoolFede/Open-Kanban