doc: due to history fix asciidoctor#192, minimum reveal.js version is…

… 3.7

README.adoc

@@ -101,7 +101,7 @@ NOTE: For some reason, when you use the system Ruby on Fedora, you also have to
 . Optional: Copy or clone reveal.js presentation framework.
   Allows you to modify themes or view slides offline.
 
-  $ git clone -b 3.6.0 --depth 1 https://github.com/hakimel/reveal.js.git
+  $ git clone -b 3.7.0 --depth 1 https://github.com/hakimel/reveal.js.git
 
 
 === Rendering the AsciiDoc into slides
@@ -112,7 +112,7 @@ NOTE: For some reason, when you use the system Ruby on Fedora, you also have to
 . Generate HTML presentation from the AsciiDoc source
 
   $ bundle exec asciidoctor-revealjs \
-    -a revealjsdir=https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.6.0 CONTENT_FILE.adoc
+    -a revealjsdir=https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.7.0 CONTENT_FILE.adoc
 
 . If you did the optional step of having a local reveal.js clone you can
   convert AsciiDoc source with
@@ -698,7 +698,7 @@ Default is built-in [path]_lib/css/zenburn.css_.
 |<file\|URL>
 |Overrides reveal.js directory.
 Example: ../reveal.js or
-https://cdnjs.com/libraries/reveal.js/3.6.0[https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.6.0].
+https://cdnjs.com/libraries/reveal.js/3.7.0[https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.7.0].
 Default is `reveal.js/` unless in a Node.js environment where it is `node_modules/reveal.js/`.
 
 |:revealjs_controls: