Add a basic user guide to the README.

[sidrus]

The readme file should have a "Getting Started" section that walks new users through the steps of

• Adding parts
• Explaining the KSP part options
• Walkthrough of the web UI features

Would be nice to have some pictures, too.

[StoneBlue]

I'll try to add some pics as I continue testing thru the next few days ;)

[sidrus]

Thanks!