Readme is missing links to documentation

[ixje]

I think readme.md should have a small section linking to

• https://github.com/neo-project/neo-debugger/blob/master/docs/debug-config-reference.md
• https://github.com/neo-project/neo-debugger/blob/master/docs/debug-evaluate-reference.md

The first is essential to even get started when using this project in standalone mode (as opposed to through visual blockchain devtracker)