Updates Python Installation Instructions
Updates Python Installation Instructions

Updates Python version to 3.6.8 to match QuantConnect Cloud (DockerfileLeanFoundation) as well as pandas and wrapt versions.
StefanoRaggi/Lean,QuantConnect/Lean,AlexCatarino/Lean,jameschch/Lean,jameschch/Lean,StefanoRaggi/Lean,AlexCatarino/Lean,JKarathiya/Lean,JKarathiya/Lean,StefanoRaggi/Lean,jameschch/Lean,AlexCatarino/Lean,AlexCatarino/Lean,StefanoRaggi/Lean,JKarathiya/Lean,StefanoRaggi/Lean,jameschch/Lean,QuantConnect/Lean,QuantConnect/Lean,QuantConnect/Lean,JKarathiya/Lean,jameschch/Lean