Add partial Linux compilation instructions.

[Sjors]

These instructions should make it easier to compile on Linux.

However, I couldn't figure out all the steps...

[erikzhang]

Did you view the documentations on docs.neo.org?

[Sjors]

I read the English instructions here, but they don't explain how to compile.

[erikzhang]

dotnet publish -c Release

[Sjors]

Thanks. I'll try that and update the README. I was also able to run the downloaded binary on Ubuntu.

[Sjors]

I updated the instruction to show two alternatives: using the pre-compiled binaries from Github or compiling from source. In both cases show state returns information, so I guess it works.

create wallet throws error though, but that might be a separate issue.

[Sjors]

If you don't add .db3 to wallet file name, it will throw error. I added an example command that works (create wallet wallet.db3).