add intro to reusable code for #95

code-reuse-publishing-to-hexpm.md

@@ -17,21 +17,89 @@ Along the way we will demonstrate how to:
 3. Publish a package to Hex.pm
 4. Use the code it in a different project.
 
+## Quotes?
+
+A quotation or quote
+is the repetition of someone else's statement or thoughts.
+
+Examples of popular quotes
+(_as upvoted or "liked" by the users of goodreads.com_):
+[goodreads.com/quotes](https://www.goodreads.com/quotes)
+
+
+Our objective with this code is
+to create an Elixir module that returns
+a random quote when `Quotes.random()` is invoked.
+
 # How?
 
+
 ## 1. Write Reuseable Code
 
+Our _first step_ is always to write reuseable code.
+If you are rewriting the same code
+("_reinventing the wheel_")
+in each new project
+you have not understood a
+basic principal of software engineering:
+reuse code.
+
+> "Good programmers know what to write.
+Great ones know what to reuse". <br />
+~ Eric S. Raymond - "The Cathedral and the Bazaar"
+
+
+### Documentation: Doctest
+
+https://elixir-lang.org/getting-started/mix-otp/docs-tests-and-with.html
+
+
+> "_Incorrect documentation is often worse than no documentation._"
+~ [Bertrand Meyer](https://en.wikipedia.org/wiki/Bertrand_Meyer)
+
+### Testing
+
 
 ## 2. Reuse Code _Without_ Publishing to Hex.pm
 
 
 ## 3. Publish Package to Hex.pm
 
+### What is Hex.pm?
+
 
-## 4. Use
+
+![hex.pm-home-page](https://user-images.githubusercontent.com/194400/65838440-f4e72080-e2fa-11e9-82d4-821187461804.png)
+
+
+## 4. Use the Package in a New Project
+
+
+## 4.a Basic Elixir Web Service _Without_ Phoenix
+
+## 4.b Phoenix Web Service
+
+### Q: If Phoenix is more code, why would I want to use it?
+
+**Answer**: Phoenix is great way to organise your project,
+it gives you many advanced features like a database interface,
+security and monitoring.
 
 
 ## Recap
 
+In this brief tutorial we learned how to write reusable Elixir code.
+We reused the our Quotes
+
+
+## _Modify_ or _Extend_?
+
+This example could easily be modified or extended
+for any purpose.
+
+http://quotes.rest
+
+![quotes-rest-api](https://user-images.githubusercontent.com/194400/65838802-d125d980-e2fe-11e9-93a4-12026b05932e.png)
+
 
 ## References and Further Reading