Remove obsolete ebook formats (#227)

* Add missing pic dependency on quick_ebook target

* Warn about deprecation of .mobi and .azw3 files.

* Remove kindle (azw3) from website front page

README.md

@@ -71,15 +71,14 @@ The below versions are automatically built on every push to the `main` branch.
 
 * [Download compiled .pdf version](https://www.the-bread-code.io/book.pdf)
 * [Download compiled .epub version](https://www.the-bread-code.io/book.epub)
-* [Download compiled .mobi version](https://www.the-bread-code.io/book.mobi)
-* [Download compiled .azw3 version](https://www.the-bread-code.io/book.azw3)
 
 There's an additional enhanced accessibility version using a sans serif font:
 
 * [Download compiled .pdf version](https://www.the-bread-code.io/book-sans-serif.pdf)
 * [Download compiled .epub version](https://www.the-bread-code.io/book-sans-serif.epub)
-* [Download compiled .mobi version](https://www.the-bread-code.io/book-sans-serif.mobi)
-* [Download compiled .azw3 version](https://www.the-bread-code.io/book-sans-serif.azw3)
+
+**The ebook files in .mobi and .azw3 have been retired, please let us know if
+you were using them.**
 
 ## Online HTML version (WIP)
 

website/modify_build.rb

@@ -496,11 +496,6 @@ class ModifyBuild
       EPUB (no serif): <a href="https://www.the-bread-code.io/book-sans-serif.epub">https://www.the-bread-code.io/book-sans-serif.epub</a>
     </p>
 
-    <p class="noindent">
-      Kindle: <a href="https://www.the-bread-code.io/book.azw3">https://www.the-bread-code.io/book.azw3</a><br>
-      Kindle (no serif): <a href="https://www.the-bread-code.io/book-sans-serif.azw3">https://www.the-bread-code.io/book-sans-serif.azw3</a>
-    </p>
-
     <p class="noindent">
       The full source code of the book can be found here:
       <a href="https://www.github.com/hendricius/the-sourdough-framework">https://www.github.com/hendricius/the-sourdough-framework</a>