Fixed about_strings.rb to pass tests

Learned about:
* creating strings,
* single and double quoted strings,
* escaping with backslash.

[#65851752]
Fixed about_strings.rb to pass tests

Learned about:
* flexible quoting...
* that can handle multiple lines as well,
* plus sign concatenates two strings...
* but would leave the original unmodified.

[#65851752]
Fixed about_strings.rb to pass tests

Learned about:
* += that will concatenate to the end of a string,
* shovel operator that will also append content...
* and modifies the original string.

[#65851752]
Fixed about_strings.rb to pass tests

Learned about:
* how double quotes interpret escape characters,
* and how single quotes don't...
* except that they sometimes do.

[#65851752]
Fixed about_strings.rb to pass tests

Learned about:
* double quotes used for variable interpolation,
* and that single quotes don't interpolate.
* that any ruby expression can be interpolated.
* getting a substring from a string...
* or a single character.

[#65851752]
Fixed about_strings.rb to pass tests

Learned about:
* splitting strings with different patterns,
* and joining them.
* each string being a separate object.

[#65851752]
Merge pull request #7 from mkreyman/65851752_about_strings_master

about strings master

[Delivers #65851752]