[Windows] Improve documentation for compiling local site via Lektor

Many users can't compile the local site because of lektor errors. Please review the instructions and add the errors (reported by users) and their solutions in troubleshooting section.

If you have any errors, please report them so we can document them. Be sure to mention your platform as well.

I have attached a file, please review it and include its content in the instructions Local_site_compilation_instruction_draft.txt

Disclaimer: Written by a Windows User, there might be some difference depending upon your platform.

Edit: I have updated the attachment file.