Merge pull request #34 from ahcorde/master

FIX introducction images
Merge pull request #35 from ahcorde/master

ES: ADD electric_power_systems.md and fix Images
Merge pull request #36 from ahcorde/master

erle-board.md to erlebrain + fix images
Merge pull request #37 from ahcorde/master

rename hardware/bbb+pxf.md to hardware/bbbpxf.md
Merge pull request #38 from ahcorde/master

Fix issues and speeling errors
Update README.md
Update README.md