Put references to Mobi files back in README

Author: HonkingGoose

README.asc

@@ -15,8 +15,7 @@ See link:TRANSLATING.md[the translating document] for more information.
 == How To Generate the Book
 
 You can generate the e-book files manually with Asciidoctor.
-We used to be able to build .mobi files (Kindle), but cannot do so now, see #1496 for more information.
-If you run the following you _may_ actually get HTML, Epub and PDF output files:
+If you run the following you _may_ actually get HTML, Epub, Mobi and PDF output files:
 
 ----
 $ bundle install
@@ -25,11 +24,13 @@ Converting to HTML...
  -- HTML output at progit.html
 Converting to EPub...
  -- Epub output at progit.epub
+Converting to Mobi (kf8)...
+ -- Mobi output at progit.mobi
 Converting to PDF...
  -- PDF output at progit.pdf
 ----
 
-You can generate just one of the supported formats (HTML, EPUB, or PDF).
+You can generate just one of the supported formats (HTML, EPUB, mobi, or PDF).
 Use one of the following commands:
 
 To generate the HTML book:
@@ -44,6 +45,12 @@ To generate the EPUB book:
 $ bundle exec rake book:build_epub
 ----
 
+To generate the mobi book:
+
+----
+$ bundle exec rake book:build_mobi
+----
+
 To generate the PDF book:
 
 ----