Update README with Unix examples

[JanitSri]

The command for Compile a program that uses the jar and Execute the Test file in the build instructions requires a colon instead of a semi-colon for CLASSPATH separator in Unix systems.

[stleary]

What problem does this code solve?
Path setting did not have a UNIX version in the README

Risks
Low

Changes to the API?
N/A

Will this require a new release?
No

Should the documentation be updated?
This is the documentation

Does it break the unit tests?
N/A

Was any code refactored in this commit?
N/A

Review status
APPROVED
No comment window is needed, the PR has already been up for 2 days, and no code files were changed