Fixed failing test in about_asserts.rb

* Learned that the assert method simply asks if the argument passed is true.

* Learned that assert has a second optional argument that
  contains additional information to help figure out why the test is failing.

[#65851826]
Fixed line 21, test_assert_equality: made expected_value = 2

*Learned that test_assert_equality tests to see
 if an expect value is equal to an actual value.

[#65851830]
Committing additional changes to about_asserts.rb.

[#65851826]