Fixed about_methods.rb to pass tests

Learned about:
* methods and that they can take arguments with or without parentheses...
* but sometimes missing parentheses are ambiguous,
* default values for method arguments,
* and variable number of arguments.

[#65851758]
Fixed about_methods.rb to pass tests

Learned about:
* explicit and implicit returns for methods,
* self,
* private methods,
* calling private methods in other objects.

[#65851758]