Fixed about_nil.rb File.

* I changed the _ after assert_equal true to be "true"

* I learned that unlike "null" in other languages, nil is an object.

[#65851832]
Fixed about_nil.rb file:

* I learned that when you call a method that doesn't exist,
you can rescue the exception and make some assertions on it.

* The exception we captured here was NoMethodError.

* I'm not exactly sure how Rescue works but am deducing just that is stores information.

[#65851832]
Fixes about_nil.rb file. I learned that nil has a few methods defined on it, including:

* nil.nil? = true
* nil.to_s = ""
* nil.inspect = "nil"

[#65851832]
Changed the error on line 20 Jason asked me to change [#65851832]
Merge pull request #2 from kkburr/65851832_about_nil_master

about nil master

[Delivers #65851832]